Glitches in Lemmings

[Clam]

Here I will attempt to compile a list of all known glitches in Lemmings. This thread is for the first-generation Lemmings games: Lemmings, Oh No! More Lemmings, and Xmas/Holiday Lemmings. Lemmings 2 has its own thread, here. The primary focus is DOS Lemmings of course, but I will try to include ports of the original game as well. Do note, though, that I only have a few versions, and I don't intend to hunt them all down. If you have any of the more obscure ports, please feel free to contribute http://www.lemmingsforums.com/Smileys/lemmings/smiley.gif" alt=":)" title="Smiley" class="smiley" />

I have attempted to categorise glitches, to keep the list organised. At some point, the more noteworthy glitches, as well as screenshots of glitches in action, could be put up on the Wiki.

I have closed the old glitch thread, and I will try to maintain this one. Frankly, the whole "spoiler warning" thing was just silly http://www.lemmingsforums.com/Smileys/lemmings/tongue.gif" alt=":P" title="Tongue" class="smiley" />

For further useful (but less gamebreaking http://www.lemmingsforums.com/Smileys/lemmings/tongue.gif" alt=":P" title="Tongue" class="smiley" />) tricks, see the non-glitch tricks topic.


DOS

Climbers

• When a climber encounters a ceiling and falls down, it comes away from the wall by one pixel, instead of falling down right next to the wall.
• Because of the way climbers check for terrain above them, they can either climb through small overhangs at the top of a wall, or fall down when there is a tiny gap (which it should be able to get into) with terrain hanging above. The outcome depends on the height of the wall.
• (Original Lemmings only) Assigning the climber skill to a shrugger causes the lemming to start moving straight away, and remain in the shrugging position while it moves on.
• If the terrain that the climber is on is removed, it hoists immediately and converts to a walker in mid-air for one frame, during which it is possible to assign a skill.
• If a lemming trapped inside terrain is made a climber, or a climber becomes trapped in terrain, it repeatedly begins climbing, gets stuck, and falls slightly. It gains one pixel in height each time. Because climbers transitioning to fallers are shifted across slightly, the wall has to be at least 4 pixels wide for this to work.
• If a lemming climbing up a thin wall encounters a blocker on the other side of the wall, it will go through the wall.

Floaters

• Floating lemmings can enter exits, even if there is no terrain under the exit trigger. This only works from the moment they deploy the umbrella, not in the first few pixels of a fall.
• (Glitch arguable) Floaters always survive a fall, even if they are assigned the skill near the ground and there isn't time for the umbrella to open.

Bombers

• If a bomber is not placed on steel when it explodes, it removes all terrain in the explosion mask, including steel. If it is on steel, it removes no terrain at all.
• Falling ohnoers can enter exits, even if there is no terrain under the exit trigger.
• After exploding, the lemming's position is shifted upwards by a few pixels. (Not reproducible in the Lemmix editor, since this removes the lemming as soon as it explodes.)

Blockers

• The blocker's area of influence overwrites steel and trigger areas. This makes it possible to destroy steel by placing a blocker next to it, and disable the effects of traps, one-way walls and exits.
• If you assign a bomber skill to a blocker, and remove the terrain under it during the 'oh no' so that it falls before exploding, its blocking area remains in place. Any steel or trigger areas that were canceled by the blocker are put back where it explodes, instead of where it was placed.
• Blockers can push lemmings through walls. This happens because lemmings cannot move towards the center of the blocking area (which is how blockers work), so a lemming inside this area can't turn around until it leaves the area - even if there is terrain in the way. (Combined with climbing in walls, this is known as the "Tame 20" glitch, after the level where it was used to achieve a no-builder solution. Note that you have to remove the blocker for this to work.)

Builders

• The "Giant Leap" or "sliding" glitch: A lemming encountering a step of 3-6 pixels will "jump" up it. The game checks each frame to see whether the lemming has reached the top of the step, instead of stopping when it reaches the initial height of the step. Thus, if you can add terrain (using a builder) at the top of the step, the lemming will continue jumping.
• Builders only check for terrain at one pixel above them, but they move forward two pixels at a time. This means they can build through one-pixel-wide overhangs.
• Right-facing builders place bricks one pixel further in front of them than left-facing builders. This affects the potential length of a bridge that can be made by "stretching" bridges (delaying each builder assignment until the last possible frame). Additionally, this means right-facing builders can always bash when they reach a wall, whereas left-facing builders will turn around as soon as they hit the wall if they were only one pixel away after laying the previous brick.
• The builder skips a check for terrain on the last brick, so if you assign a builder an exact bridge length (or slightly less) from the wall, it can build further into the wall than normal, and shrug instead of turning around.
• While builders turn around when they encounter a ceiling, it is possible to assign more builders closer to the ceiling. This means lemmings can get stuck in ceilings, and build up through thin floors.
• Similar to the above, lemmings can get stuck at the top of the map. At this point, it is no longer possible to (normally) assign builders.
• It is possible to assign builders to lemmings stuck at the top of a map, by having a blocker under the cursor, so that the stuck lemming has second priority for selection.
• Turning a builder with a blocker between placing a brick and stepping onto it causes a fake brick to appear for a moment, and leaves a tiny hole in the bridge that lemmings cannot  get across.
• If you assign a builder to a lemming as it turns around at a one-pixel wide wall, and then turn the builder with a blocker before the first brick is placed, the builder will go through the wall and continue building.

Bashers

• Bashers check for terrain only every second stroke, starting with the first.
• Bashers remove all terrain within their destruction mask, including steel.
• The basher's terrain-destruction mask includes the column of pixels that the lemming is in. Since lemmings walk into the wall slightly when they turn around, it is possible to remove steel and one-way walls by assigning a basher to a lemming as it turns around.
• Bashers can be stopped mid-stroke to leave a small upward ramp.
• Bashers check for steel higher than they check for terrain, so they can bash through the top of steel.
• Bashers near the top of the level may stop randomly. If it checks for steel off the top of the screen, the game reads from a part of memory that isn't actually written to by the game. If the value happens to correspond to steel, or one-way walls facing the wrong way, the basher will stop. (In Lemmix, the basher will always go through).
• By assigning a basher where there is a wall behind it and enough terrain in front (so that it keeps going), you can place a blocker after the first stroke to make the basher flip through the wall without breaking it. Screenshot http://www.lemmingsforums.com/index.php?topic=525.msg11376#msg11376" class="bbc_link" target="_blank">here.
  
• With a specific terrain formation, a basher can fall through terrain while leaving it intact. This is best observed on Tricky 5 / Taxing 8.

Miners

• Miners remove all terrain within their destruction mask, including steel.
• Miners can be stopped mid-stroke to leave a small upward ramp.
• Apart from the initial assignment, miners only check for steel directly beneath them. This means they can break steel in front of them, and above them.
• The miner's terrain-destruction mask extends one pixel behind it. As with bashers, it is possible to remove steel (though this is slightly more problematic, since there has to be no steel directly below the lemming) and one-way walls by assigning the skill to a lemming as it turns around.
• Miners are positioned one pixel too low during the first few frames of their animation. This makes it possible to have the miner fall through the floor while leaving it intact for other lemmings to walk on, by assigning a blocker or bomber at the right moment.
• When a miner breaks through a floor, it falls one pixel too far back, making it possible to separate the miner from other lemmings.
• Miners can break left one-way walls, but not right. A miner assigned in a right one-way wall area will take one stroke and turn back.
• Miners shift across by two pixels at a time, so they can cross one-pixel-wide gaps.

Diggers

• Diggers will remove all terrain within their destruction mask, including steel.
• Diggers check for terrain in a row of 9 pixels below them, but they only check for steel in one pixel. This means they can dig away the side of steel pieces, and even continue digging while holding on to nothing but steel.
• The digger's destruction mask includes three rows of pixels: one below the lemming, one alongside and one above the lemming.
  
• When there are two or more lemmings under the cursor when attempting to assign a digger, the game doesn't check for steel under the second-priority lemming. Thus if the first priority lemming isn't on steel, but can't dig (either because it is already a digger, or it is a blocker or 'oh-no'ing bomber) the second-priority lemming will start digging, even if it is on steel. (Note: Lemmix's replay function doesn't handle this correctly)
• Digging lemmings can enter exits, even if there is no terrain under the exit trigger.
• Pausing when assigning a digger skill sometimes causes a glitch sprite to appear. (Not reproducible in Lemmix)

Interactive Objects

• "Direct drop": Lemmings falling onto the exit's trigger area will exit if there is terrain under it, even if they would splat from the fall if the exit wasn't there.
• Lemmings falling into water may be swept across sometimes, depending on the location of terrain. With a specific setup, it is possible for a drowning lemming to be swept through terrain. (See ClamSpam02 level 5, "Get Out of the Pool!)
• Object trigger areas take precedence over steel areas. This can be exploited to dig through steel.
• Objects with no effect still have a trigger. In most cases, these are placed 4 pixels above top left corner, though Dirt and Crystal exit top pieces have wider triggers, placed lower down. These "triggers" have no special effect, but still cancel steel. (Note: these triggers are missing from entrance hatches in Lemmix.)

• Some object triggers are misplaced:
  - The water in marble tileset (green "acid") has its trigger area too high - lemmings appear to drown above the surface of the water.
  - One-way walls are 4 pixels too high; in some cases it is possible to bash underneath the wall because of this.
  - Brick tileset one-way walls are twice as wide as they should be.
  - (Glitch arguable) Some exits have to be placed lower in order to work. For example, the Bubble tileset exit can never work unless it is lowered slightly into the terrain.

Level Stats

• "Nuke glitch": When the nuke is activated, the game calculates the percentage saved based on how many lemmings have been released, not how many are available in the level.
• Pausing for time: The entrance hatch begins opening a specific length of time after the level starts, at the same time the sound effect plays. If you pause the game before the hatch begins to open, the timer stops counting down while the game is paused, but the hatch still opens at the same time (or immediately after you unpause, if you wait until after the sound plays). This gives you about two seconds extra to complete the level.
• (Glitch arguable) Release rate and skills cannot be selected with the mouse while the game is paused. They can still be accessed via hotkeys.
• In the level preview screen, terrain off the left of the level appears on the far right of the preview picture.
• Using a hex editor or Lemmix, you can set release rates above 99, up to 255, and also 0. The values simply wrap around into negatives: 255 is effectively -1, 100 is effectively -156 (one lemming per 131 frames). During play, you can change the rate to anything between this negative rate and 99 - never slower than the initial rate (Lemmix handles this incorrectly). 0 appears as a blank (the same as for zero skill counts), while values from 100 to 255 use junk characters for the tens digit. Additionally, values of 255 will blink until they are changed.

Other

• "Right-click bug": If you highlight a lemming inside the cursor, then mouse over a lemming that is performing a skill, and then left-click that lemming while holding the right mouse button, the previously highlighted lemming will perform whatever skill is currently selected, even if it is outside the cursor. If the blocker skill is selected, and highlighted lemming dies in a trap before the left-click, the blocker skill will still be used, and a blocker area will be placed over the trap. (Not reproducible in Lemmix.) See this topic for more info.
  
• Info on lemmings inside the cursor (eg. WALKER 1) remains when you quit and restart a level, until lemmings begin falling from the hatch. (Not reproducible in Lemmix)

• The left side of the map acts as a wall. As with any other wall, lemmings will walk into it slightly when they turn around. With the left edge of the map, this means they are at x = -1, which is off the edge of the map. They will turn around at this "wall", even if there is no terrain under them at the moment they turn around (note: Lemmix cuts off terrain off the edge of the map, but in DOS it can continue a bit further). Some skills have unique effects when used at this position:
  - A blocker assigned at the moment it turns around stops for one frame, during which it can turn other lemmings, then continues walking.
  - A blocker used near the edge of the map can push lemmings off the edge of the map. If you remove this blocker, you can place another one and push the lemmings even further off the edge. These lemmings are no longer selectable, but they still exist in the level.
  - If a bomber's countdown ends when it is off the edge of the level (see above), or turning around at the edge, it falls down before exploding.
  - A digger assigned past the left edge of the map will dig as long as it has some terrain to hold on to, and then fall down.

Amiga

Amiga Lemmings shares most of the same glitches as DOS. However, these glitches are not present in the Amiga version:

• Nuke glitch
• Pausing for time
• Direct drop
• Continuous shrugger (assigning climber skill to a shrugging builder)

Sega Master System

• Miners can cross one-pixel gaps.
• Climbers come out slightly from a wall when they hit a ceiling and fall.
• Diggers float in mid-air for a brief moment during their animation. If you assign a blocker at this moment, the lemming will fall and become a walker.
• The clock blinks when there are less than 30 seconds remaining. If you pause while the clock is visible, and unpause when it is invisible, the timer won't count down. Thus you effectively have unlimited time for every level.
• Pausing the game when a shrugging lemming reverts to a walker causes the lemming to glitch out and cycle through animations. The lemming doesn't move in this time, making this an effective method of slowing down a lemming.
• (UNCONFIRMED) Repeatedly pausing and unpausing can cause bashers to stop moving, while walkers continue on.
• Bashers can pass through blockers, if timed well.

(Thanks to http://www.lemmingsforums.com/index.php?topic=34.msg3388#msg3388" class="bbc_link" target="_blank">Pooty for the above)

• When a digger finishes, it becomes a walker for a moment before falling. At this point, it can be assigned to bash or build in mid-air.
• Lemmings falling into water become walkers for a moment before drowning or dying to a trap (unless they have fallen too far, in which case they will splat). It is possible to assign a builder in this time, and build a bridge from the water trap. On fire objects, a second lemming is needed - the first burns after placing one brick.
• On levels with multiple entrances, when you build over one entrance, the bricks are copied onto other entrances. The same applies to exits, on levels with more than one of those. The copied bricks are solid terrain, not just graphics.

(Thanks to http://www.lemmingsforums.com/index.php?topic=34.msg5279#msg5279" class="bbc_link" target="_blank">Adam for these)

• Falling lemmings appear to repeatedly change the direction they are facing.
• Building on continuous traps (see above) disables them. Their animation freezes, and they behave as solid terrain.
• Bridges overlapping entrances/exits (including copied ones, see above) are indestructible, like steel.
• When the nuke is active, lemmings sometimes drown (when they would otherwise splat - see above) when they fall into water from above the splat height.
• Using a miner on steel causes the lemming to move backwards a little (note: they do not turn around in this version). With enough miners, you can effectively walk backwards.
• If a bomber's timer runs out at the same time as the lemming would splat, it falls into the terrain slightly before exploding.
• Through repeated pausing and unpausing, it is possible to make a basher "slide" through a wall without destroying the terrain. This even woks with one-way walls with arrows pointing the wrong way.
• A digger starting on a peak in the terrain will just take out the top of the peak and then walk on.
• Walking lemmings appear to bob up and down at random when there are many lemmings on the screen.

Windows

• The maximum safe-fall distance is incorrectly set to 66 instead of 63. This makes some levels much easier (eg. 'We all fall down').
• Lemmings can walk over the top of the level.

PSP

• Lemmings can walk over the top of the level.
• Climber falls the wrong way after mining through the floor. He seems to skip over the hole when he finishes mining. http://www.lemmingsforums.com/index.php?topic=774.msg17091#msg17091" class="bbc_link" target="_blank">See video linked here (thanks Luis).
  
  
  Mac
  
• Some terrain objects are slightly taller due to the high-resolution graphics. This can cause lemmings to turn around in places where they wouldn't in other versions. Mayhem 26 is a famous example.
• Digging skills and bombers remove all terrain within their destruction mask, including steel.
• Climbers climbing up to the top of the level can become trapped in the terrain, instead of falling back down.
• In some cases it is possible to bash through one-way walls in the wrong direction. This is likely due to misplaced trigger areas, as in DOS.

(Thanks to finlay for these)

[finlay]

On the PS1 version, which I think is the same as the Windows one programming-wise, you can also walk off the top of the screen. I believe you can also walk off the edge of the map, although I think the only level where it becomes an issue is Crazy 18.

There are a couple of places where builders don't work as expected: in particular, they will always turn around at a wall before you get the chance to bash through that wall, unless they also happen to be on their last step – ie when they transition to shrugger. So you have to be careful to place it at exactly the right distance. They also start removing steps if you get too close to the ceiling; I think on other versions the lemming just stops building. There are a couple of vids on youtube showing these.

As for the Mac version, I'm sure you'll all be familiar with everyone's ranting and raving about the Mayhem 26 graphical bugs. But there are a few glitches that I know it doesn't have:
• builders act exactly the same going left and right; you always get the chance to bash through a wall
• Nuke glitch doesn't exist; percentage is always calculated from the total number of lemmings. It surprised me that the DOS version has such a bug, since the goal is stored as a number rather than a percentage in the LVL format.
• I don't think pausing for time exists; on the DOS version, there are a pair of sounds that are always played, which are little beepy sounds corresponding to "Let's go!" and the hatch opening on other versions – and they're always played when the level starts even if you pause. On the Mac version, if you pause before the sounds are played, they won't play until you unpause. However, the Mac timer is incredibly lenient compared to other versions' timers.
• I don't think direct drop exists but I don't know what level to test it on.
• A lot of the steel glitches seem to exist, particularly the ones that stipulate that steel is destroyed by a skill such as a bomber if the lemming is not standing on steel. I don't know about the trigger-based ones, or the ones that rely on a blocker cancelling the steel area. However, my instinct seems to suggest to me that the Mac's steel detection algorithm is different from the DOS one, and I'm fairly sure it will detect steel earlier than the DOS version would.
• Diggers on the DOS version will carry on digging even if the digger itself seems to be floating over air, as the game checks all the pixels beneath the digger's tunnel. On the Mac version, there are either one or two pixels (ie DOS-sized pixels) which it doesn't check. This can be used for a quick glitch solution to We All Fall Down that uses 2 diggers (one releases the other, which leaves a tiny ledge), and can be replicated on the SNES and Genesis versions too, as far as I know.
• Bashers on the DOS version will always take an odd number of strokes, a caveat that isn't present on the Mac.
• Miners can mine through any one-way-wall (cf Taxing 13). I'm not sure about the other ones, but they definitely can break through floors and leave a one-pixel floor for other lemmings.
• Climbers climbing up to the top of the level can become trapped in the terrain – I can't think of an effective example at the moment, however. But I'm thinking about levels such as "Lemmings' Ark", which obviously you don't get on the Mac, but is an effective example of a level in which a climber must climb up to the ceiling in order to fall back. I don't think this would happen on the Mac; I think the lemming would become trapped. I'd have to confirm it, though.
• I think Miners and Bashers are much more likely to turn around at a Blocker than on other versions; on the DOS version, you can assign a miner right next to the blocker to release him, but I think on the Mac version the miner will invariably turn around before releasing the blocker. Therefore one has to be more careful when releasing blockers that the lemming doesn't turn around. For example, you might have to assign the miner quite far back, so that it is the top of his stroke that releases the blocker.

[ccexplore]

• Miners can mine through any one-way-wall (cf Taxing 13).

Presumably you mean they can mine through any one-way-wall in the allowed direction?

• Climbers climbing up to the top of the level can become trapped in the terrain – I can't think of an effective example at the moment, however.

Well, looks like Fun 17 is the earliest level you can test this out on.  How about builders, do they react differently to the level top boundary too?

[ccexplore]

Turning a builder with a blocker between placing a brick and stepping onto it causes a fake brick to appear for a moment, and leaves a tiny hole in the bridge that lemmings cannot  get across.

This one is better described with a picture:

xxxxxx
      xxxxxx
    xxxxxx

As you can see, what happens is that the blocker (who's at the right edge of the 2nd build brick) makes the builder steps up in the wrong direction, causing the 3rd brick being laid to be not quite touching the 2nd brick laid.  Walking lemmings thus won't get up the remainder of the bridge after turning around from the blocker.

Using a hex editor or Lemmix, you can set release rates above 99, up to 250.

I'm pretty sure it's actually 255 not 250.  Also it's possible to make RR 0 (displayed in the game as blank I think, rather than 0), although that's equivalent to RR 1 and therefore not that interesting.

[finlay]

• Miners can mine through any one-way-wall (cf Taxing 13).

Presumably you mean they can mine through any one-way-wall in the allowed direction?

• Climbers climbing up to the top of the level can become trapped in the terrain – I can't think of an effective example at the moment, however.

Well, looks like Fun 17 is the earliest level you can test this out on.  How about builders, do they react differently to the level top boundary too?

I think builders are the same as on the DOS version, based on how they acted in my Mountain level.

Here's a screenshot of the climber problem:
http://dl.dropbox.com/u/15543016/Trapped-climber.png" alt="" class="bbc_img" />
You should be able to see him at the top. It's difficult to describe what actually happens to get him to the top, he kinda does the transition to walker animation twice and gets trapped a couple of pixels inside the pillar. I should maybe find a way of recording it, except that a) Sheepshaver is quite jerky (at some point I might try downloading OS 7 instead of OS 9 to see if that helps) and skips frames and b) I don't know what program to use. I could potentially boot up my other machine that can run OS 9 natively, but I'd be even more at a loss for what program to use with that. One other big problem with the emulator is that the mouse cursor is black (a bug that showed up on the native OS 9 a couple of times, to be fair. i'm not sure what causes it.), which makes the game nigh-on-impossible to play, because you can only see the cursor when it's over terrain – naturally, this is when it's least useful.

Here's a builder going slightly off the top:
http://dl.dropbox.com/u/15543016/Buildtothetop1.png" class="bbc_link" target="_blank">http://dl.dropbox.com/u/15543016/Buildtothetop1.png
and here's how close to the top the builder can get before falling off his bridge. He doesn't turn back, which I believe is the same behaviour in DOS:
http://dl.dropbox.com/u/15543016/Buildtothetop2.png" alt="" class="bbc_img" />

[finlay]

For comparison, here's DOS. You should know all this already http://www.lemmingsforums.com/Smileys/lemmings/winktounge.gif" alt=";P" title="Wink-Tongue" class="smiley" />:
http://dl.dropbox.com/u/15543016/Turned-climber.png" alt="" class="bbc_img" />
Climber's just transitioned to a faller.

http://dl.dropbox.com/u/15543016/Buildtothetop3.png" alt="" class="bbc_img" />
The builder can go significantly closer to the ceiling on the Mac version; as you can see, I couldn't even reach the left wall of the chamber on the DOS version here.

Also, in a close comparison of the two screenshots, it looks like the Mac's bomber reaches about a pixel further into the pillar...

[finlay]

Following up on that bomber observation a bit, here's how the two versions compare when making climbers into bombers:

http://dl.dropbox.com/u/15543016/BombersDOS.png" alt="" class="bbc_img" />

http://dl.dropbox.com/u/15543016/BombersMac.png" alt="" class="bbc_img" />

As you can see, on the Mac version, the craters barely touch each other in the centre of the pillar. On the DOS version, there's an overlap of a whole pixel. And on both versions, the craters are asymmetrical – but on the Mac, it's the crater from the left that is "larger", the opposite to the DOS version.

----

Also, before I forget, you're right about the miners: any one-way-wall in the allowed direction.

Also, one can bash the wrong way through the one-way-wall in SNOW JOKE, which I believe is the same on the DOS version. I don't know why this is, however.

----

Also also also, it's probably worth noting that I'm now testing what happens at the top of the playfield a bit more and it seems you can only take one basher stroke at a time. Getting a trapped climber to bash will always break through the wall that he just climbed up, so he will fall back down. You can't assign the builder skill at all, and other skills seem to work as normal.

----

Ooooh, here's something quite interesting: the climber is turned by the blocker before he actually reaches the end of his climb – in fact, midway through the transition to walker. I don't know if these screenshots are very clear but here:
http://dl.dropbox.com/u/15543016/Blockclimb.png" alt="" class="bbc_img" /> http://dl.dropbox.com/u/15543016/Blockclimb2.png" alt="" class="bbc_img" />
It seems to happen right before the frame of the second screeny. Does this happen on DOS?

[DragonsLover]

Yes, I think I once experienced the Climber being turned by a Blocker. I even wonder if it's actually possible to make it flip from a wall to another while climbing. http://www.lemmingsforums.com/Smileys/lemmings/winktounge.gif" alt=";P" title="Wink-Tongue" class="smiley" />

EDIT: Yup, the Climber get flipped. Proof below. The Climber was climbing from the right side of the deeper tunnel (facing right) and once he reached the Blocker's effect area (near his arm), he flipped on the other side of the tunnel like as below.

So, yes, if there's a one pixel wall, you can make the Climber flip from one side to another of it using Blockers. http://www.lemmingsforums.com/Smileys/lemmings/laugh.gif" alt=":D" title="Laugh" class="smiley" />

[ccexplore]

Ha, looks like DragonsLover beat me to it.  Although I haven't explicit test it out, I expect you'll see the same behaviors DragonsLover illustrated on the Mac version also.  Note that it only works well if the wall the flip occurs is 1-pixel wide.  Any wider and the climber hits his head right after the flip and stops climbing.

Also also also, it's probably worth noting that I'm now testing what happens at the top of the playfield a bit more and it seems you can only take one basher stroke at a time.

Note that when Clam talks about basher behavior near top of level, he doesn't literally mean at the highest point the lemming can walk to without turning around.  Even in DOS, I believe you can get high enough that the pixels normally checked by the basher are off the level boundary, and IIRC it works out such that the game will never detect terrain pixels in that case, and so you get one bash stroke and stop, but not because of the boundary per se, just that the game doesn't detect any terrain pixels (presumably due to clipping of the graphics) at the positions beyond the top boundary.

The case of interest Clam is talking about is when the lemming is at an elevation very near the top, such that the wall in front of him is 7 or 6 (low-res) pixels tall.  That's tall enough to support continual bashing in DOS, and then because of the way the steel checking works, the calculation causes the game to look for steel areas off the normal level boundaries, which runs into the "reading garbage from memory" issue that can "randomly" stop the bashing.  On the Mac, if I recall correctly a 5-pixel (low-res) tall wall is actual enough to support continous bashing, but on the other hand as you noted, the steel detection is also slightly different, so I have no idea how together all that plays out.

[Clam]

Good points all http://www.lemmingsforums.com/Smileys/lemmings/thumbsup.gif" alt=":thumbsup:" title="Thumbs Up" class="smiley" />

There are a couple of places where builders don't work as expected: in particular, they will always turn around at a wall before you get the chance to bash through that wall, unless they also happen to be on their last step – ie when they transition to shrugger.

IIRC, that's the same in DOS. The game seems to be more lenient on the last brick when it comes to building into walls, and ceilings as well I think. I'll have to check this.

• I don't think direct drop exists but I don't know what level to test it on.

Tricky 12 is a good one for testing direct drop.

I'm pretty sure it's actually 255 not 250.

The Lemmix editor only lets you go up to 250. It would make sense for it to go up to 255 though. I should actually try it with a hex editor at some point http://www.lemmingsforums.com/Smileys/lemmings/tongue.gif" alt=":P" title="Tongue" class="smiley" />

Also, one can bash the wrong way through the one-way-wall in SNOW JOKE, which I believe is the same on the DOS version. I don't know why this is, however.

I'd guess this is due to the one-way triggers being too high, which I mentioned already.

So, yes, if there's a one pixel wall, you can make the Climber flip from one side to another of it using Blockers. http://www.lemmingsforums.com/Smileys/lemmings/laugh.gif" alt=":D" title="Laugh" class="smiley" />

Ah yes, that one features in a certain custom level. I'd say the behaviour finlay mentioned (climbers turning around at blockers) is intended behaviour, or at least semi-intended, in the same vein as turning builders or miners. Flipping through a wall is definitely a glitch though http://www.lemmingsforums.com/Smileys/lemmings/tongue.gif" alt=":P" title="Tongue" class="smiley" />

Now you mention that, I vaguely recall being able to flip a basher through a wall without breaking it.

[Adam]

Pretty hard to explain, but as I see it, the Master System version's mechanics are interesting. Essentially, every lemming becomes a walker in between changing states. So for example, when you finish digging and remove ALL terrain, you can build in mid-air. You can also bash for a very short period without anything to stand on. I'm not sure how many ways there are to exploit this, but there must be a fair few!

[finlay]

Good points all http://www.lemmingsforums.com/Smileys/lemmings/thumbsup.gif" alt=":thumbsup:" title="Thumbs Up" class="smiley" />

There are a couple of places where builders don't work as expected: in particular, they will always turn around at a wall before you get the chance to bash through that wall, unless they also happen to be on their last step – ie when they transition to shrugger.

IIRC, that's the same in DOS. The game seems to be more lenient on the last brick when it comes to building into walls, and ceilings as well I think. I'll have to check this.

DOS is strange, though; when facing right it allows you to hit the wall with the builder and then bash, but when facing left it will turn back straight away before you get the chance to bash. Essentially, the PS1 version uses the left-facing mechanic of the DOS version for both directions and the Mac version uses the right-facing mechanic. But there are very few situations that I can think of where your lemmings are travelling left in a level, so usually you might as well conclude that the DOS is the same as the Mac version... or something.

Also, I don't think you can execute the Mayhem 29 backroute on the Mac due to a similar reason; the Mac builders are more symmetrical.

• I don't think direct drop exists but I don't know what level to test it on.

Tricky 12 is a good one for testing direct drop.

OK. Maybe another day; I'm going away for a few days and I kinda need to get my stuff sorted out at the moment (also my friend's just flaked out on me at midnight and now I have to find somewhere else to stay.  http://www.lemmingsforums.com/Smileys/lemmings/angry.gif" alt=">" title="Angry" class="smiley" /> http://www.lemmingsforums.com/Smileys/lemmings/angry.gif" alt=">" title="Angry" class="smiley" /> )

[ccexplore]

IIRC, that's the same in DOS. The game seems to be more lenient on the last brick when it comes to building into walls, and ceilings as well I think. I'll have to check this.

It skips the ceiling check on the last brick.  And it may not occur to most people that way, but most of the time it's actually also the ceiling check that stops the builder building into walls (if you think about it, the ceiling indeed exists at the place where the build brick is inside the wall, just that you have more terrain right underneath that "ceiling" is all http://www.lemmingsforums.com/Smileys/lemmings/winktounge.gif" alt=";P" title="Wink-Tongue" class="smiley" />).

There is a separate check that's better called "floor check", which isn't skipped on the last brick.  You can see the difference between the ceiling-check wall behavior vs. the floor check wall behavior as follows:  try building after digging down say 7 pixels, vs after digging down say 12 pixels.  Notice the difference in how many steps the game lets you build in the two cases.  In the former, you are not low enough to trigger a ceiling check, so only with the floor check is your building stopped.  In the latter you are more than low enough to trigger the ceiling check.

• I don't think direct drop exists but I don't know what level to test it on.

I'm 99% sure I have tested the Mac before for this and found that direct-drop doesn't work.  However, as I've messed around with too many versions I could easily have mixed things up, so please feel free to re-test.

DOS is strange, though; when facing right it allows you to hit the wall with the builder and then bash, but when facing left it will turn back straight away before you get the chance to bash.

It's more understandable when you note the other asymmetry with DOS builders:  when building to the left, the build brick is actually placed such that the rightmost pixel of the brick is one pixel right of where you are standing (ie. not graphically per se, but the exact pixel the lemming is at), unlike building to the right, where the leftmost pixel of the brick lines up perfectly with where the lemming is standing.  In other words, the build bricks are effectively shifted one pixel to the right when building left, instead of perfect symmetrical with how they are laid out when building right.

This asymmetry pretty much explains the build-wall-and-bash behavior asymmetry:  it's not so much that the lemming detects the wall differently, as that the build bricks themselves basically don't quite reach as far when building left than building right.  So the case where the build brick is one pixel into the wall when building right, the mirror case building left has the build brick only just touching the wall.

Another well known effect of this asymmetry is that you can't stretch builders as far going left vs going right.

Also, I don't think you can execute the Mayhem 29 backroute on the Mac due to a similar reason; the Mac builders are more symmetrical.

I'm pretty sure I've tested it before on the Mac and it works fine, if you're talking about the "build left from start" backroute.  Because of the water, the Mac version doesn't let you dig down the steel as far as you can in DOS.  However the more symmetrical builders in Mac allows you to stretch your builders farther than the DOS version, and the two pretty much cancel out each other, allowing the left route to be viable in each version.

[Clam]

I just picked up SMS Lemmings along with an emulator, and me and Adam went and found a whole bunch of glitches http://www.lemmingsforums.com/Smileys/lemmings/laugh.gif" alt=":D" title="Laugh" class="smiley" />

- As well as water, lemmings can build on top of other things like fire and flamethrowers, however it takes two lemmings to build on fire - the first places one brick and then burns.
- Continuous traps (like fires and the spinning trap) can be disabled by building into them. Their animation freezes, and they act as solid terrain.
- Mining on steel makes the lemming move backward slightly. With enough miners, you can effectively walk backwards!
- Building over exits copies the bricks to other exits, just as building over entrances copies bricks to other entrances. Not only do these act as solid terrain on all entrances/exits, they are also indestructible like steel.
- Lemmings falling from a height onto water usually splat, but when the nuke is active they sometimes drown instead. I can't yet figure why some splat and some drown, so this needs further testing.
- One of the glitches Pooty mentioned on the old thread (freezing bashers by pausing) doesn't seem to work for me. No matter how often you pause, all lemmings, bashers or otherwise, seem to keep moving, albeit slowly. Again, needs more testing.

[finlay]

Another well known effect of this asymmetry is that you can't stretch builders as far going left vs going right.

Also, I don't think you can execute the Mayhem 29 backroute on the Mac due to a similar reason; the Mac builders are more symmetrical.

I'm pretty sure I've tested it before on the Mac and it works fine, if you're talking about the "build left from start" backroute.  Because of the water, the Mac version doesn't let you dig down the steel as far as you can in DOS.  However the more symmetrical builders in Mac allows you to stretch your builders farther than the DOS version, and the two pretty much cancel out each other, allowing the left route to be viable in each version.

Ohhh, I misunderstood – I thought that you could stretch builders further going left. To be fair, I've never actually seen the backroute done, so I wasn't quite aware that you had to dig down first (it wouldn't have occurred to me).

As for the reason why the asymmetry – the exact pixel that the lemming is standing on – I realised this when playing DOS Lemmings a month or two ago, because I was trying to be pixel perfect with something or other.