Glitches in Lemmings (old thread)

[Dullstar]

The trigger areas of water can be in the wrong place, causing a lemming to drown because it hit the trigger area instead of the terrain, because the trigger area is elevated SLIGHTLY higher.  In these cases, the lemmings are supposed to land on the terrain, not in the water.

For example, in Pea Soup,  if you put holes of the exact shape and size of the water, the lemmings would not drown instead of land on the "pea," because they would land on the "pea" like they were supposed to.  Trigger areas are only visible to the eye in the Lemmix level editor.  No wonder you'll be taken by surprise when the lemmings drown when they would normally land on the terrain instead.

[Mr Kiwi]

Just Dig! on Game Gear has no bottom floor... Well, it is there, but cannot be seen.

[Tsyu]

Just Dig! on Game Gear has no bottom floor... Well, it is there, but cannot be seen.

Really? I can see it just fine.

[Dullstar]

Could your Game Gear have a bad bottom screen?  At least, you have that large lemmings collection, so I would assume that you have the actual game.

If you aren't using a game gear, it could be a glitchy emulator.

Some games have had multiple versions, might Game Gear lemmings have been one of them?  (if you aren't sure what I'm talking about, think getting cheats.  For example, for The Legend of Zelda:  Ocarina of Time, when getting cheats you have to know if you have 1.0, 1.1, or uh, 2.0?  The last one could have been 1.2 instead, as I don't remember because I don't cheat on that game anymore).

[Clam]

I've finally figured out Wicked 7 http://www.lemmingsforums.com/Smileys/lemmings/XD.gif" alt=":XD:" title="XD" class="smiley" />.

Anyway, this isn't really a glitch, and certainly doesn't warrant the spoiler warnings associated with this thread, but it's still slightly messed up. On Crazy 18 and 19, as well as Wild 18, there is a gap between the lower edge of the water objects and the bottom of the screen. On Wild 18, there's also two water objects next to each other that are placed at different levels. With a bit of bomber timing, you can get two lemmings to drown at the same time and have one floating over the other http://www.lemmingsforums.com/Smileys/lemmings/laugh.gif" alt=":D" title="Laugh" class="smiley" />. I'll post a pic if you want, but it's pretty easy to do (you don't even need to change the release rate).

[Clam]

While searching the old forum for info on 3-trapdoor entrance order and fake objects, relevant to the 1 minute solutions thread, I've stumbled upon something else. Another steel-digging glitch. Some of you know this already - in fact, the people who posted about it are still active on this forum -  but it's new to me. It seems to work like this:

If you have two lemmings under the cursor, and the one that has priority for selection can't be assigned a digger for whatever reason (but NOT if it is standing on steel), then the game doesn't check for steel on the second-highest priority lemming. So, if you click on the lemmings with the digger tool selected, the second-priority lemming will dig even if it is on steel. It only digs down 1 pixel (since the game detects steel as normal afterwards), but you can do it multiple times in succession as long as you have the other lemming under the cursor.

Interestingly, the use of this glitch can't be saved in a Lemmix replay. There's a similar glitch where you can build with a lemming that is stuck at the top of a level, where it can't normally build, but it's not terribly useful.

[Dullstar]

Interestingly, the use of this glitch can't be saved in a Lemmix replay.

O_o

Strange.
Maybe we should make a "Glitches in Lemmix" thread which doesn't relate to any SPECIFIC glitch, but all glitches in Lemmix, which may just be something like, "Hey, x glitch doesn't work in Lemmix!"

It's certainly a lot easier to fix glitches when there are people to tell you what these glitches are!  Otherwise, a glitch could slip by unnoticed.  Of course, there are ALWAYS going to be some glitches.  I certainly wouldn't blame Nintendo for the glitch in Super Metroid that allows you to skip a whole boss just because it's so hard to pull off, therefore highly unlikely to be noticed by the testers!  Things like that could occur in any given game project.

[Clam]

(whoa, this just turned into a wall of text. key points in bold)

Here's something I just found while using the cursor steel-digging glitch on Mayhem 12. Keep in mind here that the steel area matches up exactly with the steel terrain.

After using the glitch to get through most of the steel, the remaining piece is at least 8 pixels across (this is the furthest you can get with the first digger still under the cursor). To get through this width of steel takes at least two basher strokes (the most you can take out at once is 7 pixels), which should mean the basher doesn't work at all. And yet it goes through. http://www.lemmingsforums.com/Smileys/lemmings/huh.gif" alt="???" title="Huh?" class="smiley" />

I'm testing things as I type this. It only seems to work when the basher is above the level of the floor where the exit is. If I try it at floor level, or more than 4 pixels above, it doesn't work.

And it gets weirder. I move the exit away and it stops working. If I move the exit to the left, it lets me bash through the left part of the steel. And a bit more testing shows that it's caused by the exit top, not the exit itself. Other objects don't seem to work. Wherever I move this object (or place new ones), the steel becomes destructible below the left side of it.

Now I'm sure you're curious and want to see this for yourself. Open up the level (Mayhem 12, "The Far Side") in Lemmix and do the following:

- Move the top part of the exit down 4 pixels.
- Copy the object and place two more, one 8 pixels to the left and the other 16 pixels to the left
- Run the level and bash through the steel.
And then move some things around to see what happens.

I'm going to test it in DOS now. I have my doubts as to whether it will work...
EDIT: Wow, it works in DOS. http://www.lemmingsforums.com/Smileys/lemmings/shocked.gif" alt=":o" title="Shocked" class="smiley" /> However, I've only got it to work in the dirt tileset. It works for miners, diggers and bombers too, if you use them in the right spot.

Mayhem 12 is the only level where this has any effect. I checked Tricky 27, but the areas don't overlap at all. In theory, this works for VGASPEC levels too. The original special graphics levels don't have steel though. (Don't worry geoo, Supaplex Tricks isn't affected http://www.lemmingsforums.com/Smileys/lemmings/wink.gif" alt=";)" title="Wink" class="smiley" />)

I've pinned down the exact area affected. See the attached screenshot. The trigger area on the left is the area where steel is canceled by the exit top piece (I placed a coupe of rock traps to make this). It lines up with the DOS grid, so (for example) moving the object one pixel to the left has the same effect as moving it 4 pixels to the left - the breakable steel area moves left by 4 pixels.

[Clam]

Split into a second post to avoid confusion... here's the other thing I wanted to mention. This relates to bombing through steel with blockers. When I did the following (on Tricky 9, it will likely work on other levels too):

- Let two lemmings out at RR99
- Set the first one to bomb, then the other about half a second later
- When the first one stops walking, turn the second one into a blocker

The first lemming explodes and makes a hole in the steel, and then the second one falls and explodes. However: If the second lemming falls to the lowest part of the hole created by the first (that's 8 pixels down - this will happen if you place the blocker close to the first lemming), the explosion doesn't make a hole (and because it's a blocker, you can't place another blocker to make it blow a hole). Otherwise (7 pixels falling or less), it does make a hole. As a result, you can get through 15 pixels of steel with this setup, but not 16. Obviously, you can get through 16 with a different setup, but that's not the point.

Can you (ccexplore or anyone else) explain this? Does the falling blocker cross some invisible threshold between 7 and 8 pixels?

[ccexplore]

And it gets weirder. I move the exit away and it stops working. If I move the exit to the left, it lets me bash through the left part of the steel. And a bit more testing shows that it's caused by the exit top, not the exit itself. Other objects don't seem to work. Wherever I move this object (or place new ones), the steel becomes destructible below the left side of it.

Yep, that's correct.  DOS Lemmings does not actually have a way for an object to specify "no trigger area" (other than fake objects, ie. index 16 or higher).  So for decorative objects like the exit top, the best it can do is to specify the smallest trigger area possible (4x4) in what's supposed to be the upper corner of the object (but because of the same miscalculation that places one-way-wall trigger areas off by 4, it's more like (0,-4)), and set the trigger area effect to "none".  And because objects' trigger areas override steel, you get the behavior you see in Mayhem 12.

[edit: hmm, actually based on your picture and your description, it seems that the area being canceled out is much lower than I expected.  I'll have to check groundXo.dat for the dirt set to see if the positioning of the exit-top object's trigger area is in the unusual position depicted in your screenshot]

[edit2:  okay, it looks like in the dirt and crystal sets (0 and 4), the exit-top has an unusual 8 (width) x 4 (height) trigger area at (x+4,y+12) where (x,y) is the object's position, which matches with your screenshot.  I haven't looked at other types of objects or the ONML/Holiday graphics sets in detail yet to say whether there are anything unusual in those.]

In original Lemmings/ONML, the only other types of object that has such a trigger area setup are the entrance trapdoors, and the flag objects (which aren't used in any 1-player levels).  Holiday Lemmings however, I think every type of object except the exits would have this trigger area setup, although I don't know if there are any levels where you can make use of it.

This was mentioned (though not in the context of steel-destruction glitches) obliquely in http://camanis.net/lemmings/files/docs/lemmings_vgagrx_dat_groundxo_dat_file_format.txt" class="bbc_link" target="_blank">my documentation on groundoX.dat files.

Note that because Lemmix doesn't properly handle object indices, it's good to double-check applications of this in the actual DOS game, to make sure the object causing this effect isn't fake in the actual DOS game.

[ccexplore]

When I did the following (on Tricky 9, it will likely work on other levels too):

- Let two lemmings out at RR99
- Set the first one to bomb, then the other about half a second later
- When the first one stops walking, turn the second one into a blocker

<snip>

Can you (ccexplore or anyone else) explain this? Does the falling blocker cross some invisible threshold between 7 and 8 pixels?

You're seeing the http://www.lemmingsforums.com/index.php?topic=34.msg886#msg886" class="bbc_link" target="_blank">Wicked 7 glitch in action, together with the effects of alignment on trigger areas.  The blocker's field is setup starting at (x-4,y-6) [actually, rounded down to nearest multiple of 4 to align with grid].  In the context of Tricky 9 you get the following:

Code: [Select]

...
.L.
SSS
where "." is air, L is where the blocker is standing (also air), and S is the first 4 rows of pixels of steel the blocker is standing on.

Because of the Wicked 7 glitch in your setup, when the blocker finally explodes, the game restores the saved trigger areas above into the blocker's new position after it has fallen into the explosion pit of the first lemming.  But the restored trigger areas must align with the DOS grid, whereas the blocker's new position doesn't.

The end effect is that in both the case of 7 pixels down and 8 pixels down, even though the blocker's final position is different, the trigger areas are restored in the same position in both cases.  Namely, the top 8 rows of pixels of steel turns into nothing.

Code: [Select]

...    ...
.L.    ...
SSS -> ...
       .L.
       SSS
But the blocker would be standing immediately above the steel in the 8-pixel case, and not in the 7-pixel case.  So no steel taken out in the former but in the latter.

[Clam]

[edit: hmm, actually based on your picture and your description, it seems that the area being canceled out is much lower than I expected.  I'll have to check groundXo.dat for the dirt set to see if the positioning of the exit-top object's trigger area is in the unusual position depicted in your screenshot]

I was just about to mention that before you edited it in. It might be worth checking the files for the positions of these areas on other objects, just in case. I just checked another exit top (Pillar tileset) and it is as you described - the "trigger" area is above the left corner.
(edit: I'm trying it with a trapdoor now (dirt tileset) and it isn't working. This one must be different too)

Note that because Lemmix doesn't properly handle object indices, it's good to double-check applications of this in the actual DOS game, to make sure the object causing this effect isn't fake in the actual DOS game.

Along these lines, is this "bug" specific to DOS, or does it affect Amiga too? If it does, there might be potential for different results in Amiga (or the corrected DOS version, for that matter) in levels where water objects bring the total number of objects to more than 16.

But the blocker would be standing immediately above the steel in the 8-pixel case, and not in the 7-pixel case.  So no steel taken out in the former but in the latter.

Thanks. That makes sense. http://www.lemmingsforums.com/Smileys/lemmings/thumbsup.gif" alt=":thumbsup:" title="Thumbs Up" class="smiley" />


(edit) One more thing...

And because objects' trigger areas override steel, you get the behavior you see in Mayhem 12.

I just realised, that applies to ALL trigger areas, not just these fake ones (and one-way walls, which I mentioned earlier). And that means...
It IS possible to drown the lemmings in Flurry 8, Vacation in Gemland. I've always wanted to do that. http://www.lemmingsforums.com/Smileys/lemmings/laugh.gif" alt=":D" title="Laugh" class="smiley" /> http://www.lemmingsforums.com/Smileys/lemmings/laugh.gif" alt=":D" title="Laugh" class="smiley" /> http://www.lemmingsforums.com/Smileys/lemmings/laugh.gif" alt=":D" title="Laugh" class="smiley" />

[Dullstar]

(whoa, this just turned into a wall of text. key points in bold)

Here's something I just found while using the cursor steel-digging glitch on Mayhem 12. Keep in mind here that the steel area matches up exactly with the steel terrain.

After using the glitch to get through most of the steel, the remaining piece is at least 8 pixels across (this is the furthest you can get with the first digger still under the cursor). To get through this width of steel takes at least two basher strokes (the most you can take out at once is 7 pixels), which should mean the basher doesn't work at all. And yet it goes through. http://www.lemmingsforums.com/Smileys/lemmings/huh.gif" alt="???" title="Huh?" class="smiley" />

I'm testing things as I type this. It only seems to work when the basher is above the level of the floor where the exit is. If I try it at floor level, or more than 4 pixels above, it doesn't work.

And it gets weirder. I move the exit away and it stops working. If I move the exit to the left, it lets me bash through the left part of the steel. And a bit more testing shows that it's caused by the exit top, not the exit itself. Other objects don't seem to work. Wherever I move this object (or place new ones), the steel becomes destructible below the left side of it.

Now I'm sure you're curious and want to see this for yourself. Open up the level (Mayhem 12, "The Far Side") in Lemmix and do the following:

- Move the top part of the exit down 4 pixels.
- Copy the object and place two more, one 8 pixels to the left and the other 16 pixels to the left
- Run the level and bash through the steel.
And then move some things around to see what happens.

I'm going to test it in DOS now. I have my doubts as to whether it will work...
EDIT: Wow, it works in DOS. http://www.lemmingsforums.com/Smileys/lemmings/shocked.gif" alt=":o" title="Shocked" class="smiley" /> However, I've only got it to work in the dirt tileset. It works for miners, diggers and bombers too, if you use them in the right spot.

Mayhem 12 is the only level where this has any effect. I checked Tricky 27, but the areas don't overlap at all. In theory, this works for VGASPEC levels too. The original special graphics levels don't have steel though. (Don't worry geoo, Supaplex Tricks isn't affected http://www.lemmingsforums.com/Smileys/lemmings/wink.gif" alt=";)" title="Wink" class="smiley" />)

I've pinned down the exact area affected. See the attached screenshot. The trigger area on the left is the area where steel is canceled by the exit top piece (I placed a coupe of rock traps to make this). It lines up with the DOS grid, so (for example) moving the object one pixel to the left has the same effect as moving it 4 pixels to the left - the breakable steel area moves left by 4 pixels.

(wall of text, will not be edited to determine what is being looked for).  Do you have to perform the steel glitch for this to work?  Nope!  That's what makes this the perfect glitch!  Heh heh, easy to perform.

[ccexplore]

[edit2:  okay, it looks like in the dirt and crystal sets (0 and 4), the exit-top has an unusual 8 (width) x 4 (height) trigger area at (x+4,y+12) where (x,y) is the object's position, which matches with your screenshot.  I haven't looked at other types of objects or the ONML/Holiday graphics sets in detail yet to say whether there are anything unusual in those.]

I browsed through all the sets in Lemmings, ONML and Holiday Lemmings, and it looks like the two objects mentioned above are the only ones that have the "unusual" trigger area.  All the other ones are the usual (x, y-4) 4x4 triggers.

The browsing did bring to attention that in ONML, some of the traps are also split into two parts like the exit, and the part that's not animated would have a potential steel-canceling trigger area.  This includes the left and right lizard traps in set 1, and the golden horizontal "zap gun" trap in set 3.

[Clam]

What about trapdoors? I've tried a few of these and they don't seem to cancel steel in that spot.