[Lemmings 2] Minimum skills for gold

[geoo]

To round out Highland (well, except for the two levels at the beginning still missing; now who's gonna try 'A mere stone's throw'? http://www.lemmingsforums.com/Smileys/lemmings/tongue.gif" alt=":P" title="Tongue" class="smiley" />), here are the scores for the last two levels:

Highland IX: 7 skills (It's possible to guide the lemming with the icarus wings through the narrow path at the top; you still need two Flame throwers and platformers each to set up the way for the crowd though - while you can get through with one flame thrower, the platform will end up too high then.)
Highland X: 3 skills (Nothing new there, save perhaps for flinging lemmings out of the water that are already drowning, but it's nice because it's surprisingly easy to execute.)

[LemSteven]

Rounding out Circus:

Circus 8 -- 8 (More abuse of the crawling trick; see below)
Circus 10 -- 10 (Pretty much the standard solution)  Edit:  See geoo's improvement below.

And to finish up Shadow:

Shadow 9 -- 3 (More roper-induced crawling)

Follow the regular solution until you get to the right side of the level.  Make a lemming a scooper at the far right edge of the level, and then make him jump mid-scoop.  If you jump him at the right time, there should be a small step at the right side of his tunnel that the lemmings can walk up. 

The next part is where you set up the crawling trick.  Make a lemming platform left from the little step in the tunnel.  He will lay down two bricks and hit the other side of the tunnel.  From this platform, build another platform going right.  Finally, stomp at the far left edge of the first platform.  The stomper should only take one stomp and then walk off to the right.  As long as the right ends of the two platforms are still intact, the lemmings should get stuck in the little step, triggering the crawling trick.

The lemmings should crawl all of the way up to the very top-right corner of the level and walk to the left.  All that's left to do is stomp when you're over the exit.

[geoo]

I got Circus X down to 8 using a crawling route again. Some screenshots are attached. I might be possible to get this route down to 7 skills, but I'm not sure whether the timing works out:

After scooping, club bash through one of the pedestals to allow one lemming to get ahead. Have him platform under the steel which goes up to the top. The crowd should be on its way while the platformer is not fully done; at that point use a filler. Part of it will go beyond the platform, while the rest will be kept on it. If done correctly, there should be a 1-pixel step on the platform now. Use the stacker to decrease the width of that step to 1 pixel and get one lemming up to scoop to the exit. Use the second platformer to create the 1 pixel wide gap required for crawling. As the platformer will face left at the top, you'll have to use an additional filler.
It might be possible to first use the platformer, and then have that lemming stack so that no-one will walk to the left at the top, however the following lemmings seem to be so close that the scooper gets taken over, so that depending on where you scoop, some lems will either walk into the wrong direction on the elevated ball, or splat on the pedestal.

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Nice work on the last levels of Cavelem, especially 'Wilma!'. I wouldn't have thought it'd be possible to get VIII and IX down that far!
Cavelem proved to have pretty interesting solutions in general, like Outdoor did; though I managed to get the Outdoor score improved by 1 down to 40, as I found a 4-skill solution to Outdoor IV 'Deliverance', one screenshot attached:

Make the first lemming roper at the edge; while he's setting up the roping device, have the second one start glueing. Have the roper shoot backwards, so that the glue goes over a 1-pixel overhang of the hook. When he falls into to water, give him a kayak, while having a second lemming glue another time at the top.

[ccexplore]

I managed to get the Outdoor score improved by 1 down to 40, as I found a 4-skill solution to Outdoor IV 'Deliverance', one screenshot attached:

Excellent! http://www.lemmingsforums.com/Smileys/lemmings/thumbsup.gif" alt=":thumbsup:" title="Thumbs Up" class="smiley" /> I've been wondering about 4-skill solution on that level ever since seeing this http://tle.vaarties.nl/lemmings2/solutions/amiga/outdoor/4/" class="bbc_link" target="_blank">rather sketchy screenshot from the Lemmings Encyclopedia  http://www.lemmingsforums.com/Smileys/lemmings/undecided.gif" alt=":-\" title="Undecided" class="smiley" />.  Needless to say I never got it to work like that questionable screenshot (though to be fair, it could be a weird Amiga/PC difference, and Simon did say he had once seen a partial rope when roping near the water surface, but hasn't yet been able to replicate that feat).  Never thought of using the roper the way you did!

[geoo]

Despite using the Lemmings Solution (or now called Encyclopedia) for reference if I don't remember a level offhand, I never actually look at the solutions depicted, so I didn't notice that yet. So I started up WinUAE with Lemmings 2 (now I know where the 'ouch' sound comes from that the Lemmings make when landing on their back in L++, in my DOS L2 it doesn't sound as nice, though perhaps there's a CD version again), and tried this solution. While my solution doesn't work as you cannot assign a skill while aiming with the roper/archer (the latter which I noticed works as well in DOS for this solution, and is even easier to execute), there's a 3-skill solution in the Amiga version, similar to the one depicted on the Lemmings Encyclopedia, just without using the kayaker. It's some subtle difference that makes it work: the anchor the roper sets has an T-shape, while on DOS it's an I-shape. It's similarly subtle like the difference that allows to solve Egyptian X with 3 skills and Space I with 1 on the Amiga, using the mortar to get through the 8-pixel floor from the top, while in DOS you can only get down 7 pixels. Another difference I noticed is that you can accelerate the icarus wings horizontally on the Amiga, so it's likely there are more subtle differences like this.

Are you sure you can rule out the Tarzan route (which is amazing, btw) for Highland VIII just because of the time limit? Sending the lems over with the cannon should take about 3 minutes if you send them over in packs of 2 every fourth lemmings, or just send over every second one, so the chain frequency equals the lemming frequency (and I'm not even sure whether it matches as perfectly as in 'Odyssey', for some reason). I think more of an issue is actually executing it, because it seems incredibly tough to land every single one in the thin basher tunnel. Also because apparently the chain doesn't catch the lemmings when they get flung directly from the cannon, you'll end up using 3 skills, as you can't both change their directions and turn them into regular fallers without the platformer at the right. Would still be an improvement over the current record though, but I wonder whether it's humanly possible.

[LemSteven]

Nice job ccexplore with your Highland 2 and 4 solutions!  http://www.lemmingsforums.com/Smileys/lemmings/thumbsup.gif" alt=":thumbsup:" title="Thumbs Up" class="smiley" />

Right now the best I've got for Classic 8 is 11 skills.  It's pretty much just the standard solution, using a climber, a blocker, a builder, two bashers, a miner, and five diggers.

I've also had a go at Egyptian 10, and it appears that the 3-skill solution shown in The Lemmings Encyclopedia does not work because the mortar's crater isn't quite big enough to break through the floor.  I was still able to use the same general idea elsewhere for a 9-skill solution.  (See spoiler below)

Use five sand pourers to get everyone out of the first pit.  Before anyone starts walking down the stairs to the left, make the leader a glue pourer.  This will prevent anyone from falling past this stairway.  Now pick a lemming who is walking up the stairs and make him a mortar so that everyone can get into the tiny room on the right.  Finally, make use two glue pourers in this room to fill the gaps in the passageway ahead.

[ccexplore]

Starting a new post for new results:

Space X: improved to 8 skills.  A slight modification of my 9-skill solution that finally can get everyone out of the pit in 2 skills instead of 3.  See spoiler/screenshot for details.

Beach V: improved to 3 skills by eliminating waste of skills purely for crowd control.  See spoiler/screenshot for details.

Beach VII: improved to 10 skills.  The standard solution actually is doable in 11 skills if you do it right.  For 10 skills, we take a shortcut using some precision moves with the tree left of the red bucket.  See spoiler/screenshot for details.

Beach X:  improved to 4 skills by eliminating waste of skills purely for crowd control, using some precision moves.  See spoiler/screenshot for details.

[edit: added more results below Mar 21 2010]

Circus V:  standard solution improved to 4 skills, again by minimizing crowd-control skill waste.  See spoiler/screenshot for details.

Egyptian IX: got 8 skills via a crawling route.  See spoiler/screenshots.

Egyptian X: improved to 7 skills, thanks to one of the glitches ClamSpammer discovered a while ago, making it possible to get a lemming outside the pyramid in 3 skills.  See spoiler/screenshots.

[edit: start new zip file for new results below]

Polar II: improved to 5, no 4 skills.  Most likely a slight improvement to the same solution LemSteven first reported. (Actually on second thought, maybe this is totally new.)  Borderline glitch(es)?  See screenshots/spoiler.  Okay, I've now improved it down to 3 skills http://www.lemmingsforums.com/Smileys/lemmings/cool.gif" alt="8)" title="Cool" class="smiley" />!  See spoiler/screenshots for details.

Polar V:  improved to 8 skills.  Miscellaneous improvements from standard solution.  See screenshots/spoiler.

[edit: more results, I think Classic is the only tribe left that I haven't looked at in detail]

Polar III: finally improved to 3 skills.  Took forever to come up with where to rope to trigger crawling.  See screenshots.

Polar IX: improved to 6 skills.  Another roper-induced crawling, a little easier to discover.  See screenshots/spoilers.

Shadow VIII:  improved to 5 skills.  And you don't even need the cannon-pause trick!  See screenshots/spoilers.

Shadow X: improved to 8 skills.  See screenshots/spoilers.

By the way, Simon, there's a typo in your table.  Space X is 8 not 6.  The total for Space (54) is correct though.

Space X:  have 1st lemming out bazooka to the left at the position shown in screenshot A.  This will fling the 2nd lemming (our hero) barely out of the pit, as shown in screenshot B.  When hero walks to about the center of the middle of the 3 steel blocks, have the lemming in the pit that just turned around the left wall to fire bazooka to the right (screenshot C).  Then quickly assign hero runner and then jumper at exactly the positions shown in screenshots D and E.  The running jump plus the bazooka explosion's knockback, timed correctly, will be able to get the hero onto the exit platform (screenshot F).

Hero will fire bazooka to turn himself around, then pour glue.  Let him run back to the left and into the right half of the pit.  Now wait for everyone to come out of the entrance, then have hero fire bazooka to the left, pressing against the barrier separating the two halves of the pit (see screenshots G).  This will accomplish 3 things:

1) fling your hero out of the pit so he can exit
2) completely remove the barrier (for some reason, it wouldn't work quite right if you try to do this from the left half of the pit)
3) the knockback will fling the crowd against the left wall of the pit, resulting in the crowd being more compressed

The compression of the crowd will enable you to get everyone out using just one more bazooka (screenshots H and I).

Beach V:  Starting fencing through the obstacle at exactly the position shown in screenshot A.  This will work out to create maximum (well, sufficient anyway) separation between frontmost lemming and the one behind it, when fencer breaks through (screenshot B).  Then have the front lemming build, and as soon as the build brick is laid down, even before he steps up onto it, start pouring (screenshot C).  The glue will be ready just in the nick of time to ensure everyone gets to the exit (screenshot D).

Beach VII:  Here's the shortcut: when the hero lemming gets to near the top of the tree left of the red bucket, assign him miner at exactly the position shown in screenshot A.  Now watch the miner's animation and wait until he starts taking a step down, then assign him jumper (screenshot B).  His jumping will reflect off the tree's leaves on the right, make him end up on top of one of the tree's left leaves facing left (screenshot C).

Beach X:  Scoop at exactly the positions shown in screenshots A and B, as soon as possible.  The end result will be screenshot C, in which you maximize the separation of the frontmost lemming from the rest.  Then complete the rest of the path using 2 archers, as shown in screenshots D-F.

Circus V:  The only crowd control is to have 2nd lemming bash at position shown in screenshot A, to give sufficient delay to allow first lemming to platform to seal off the right end.  Then have lemming scoop to the left near the top, at position shown in screenshot C.  This will basically allow him to break through so close to the top that it only takes one platform-brick to bridge the gap to the exit, which you can do in time (screenshots D, E).

Egyptian IX:  Bash through the first obstacle, and then start stomping very close to the trap trigger (screenshot A), which should prevent anyone from triggering the trap.  Then use a basher, 2 stompers and 2 bombers to pave the way through to the area below the exit (screenshots B and C).  Note that you must assign the final bomber at a height below the nearby steel block's top surface in order to break through (screenshot B).  This is possible because the stomper stops stomping only after he gets below the steel, and if he's sufficiently to the left, the leftmost columns of pixels of the stomper tunnel will be off the steel and therefore can be taken out.  Finally platform at place shown in screenshot D to trigger crawling.

Egyptian X:  ClamSpammer's hopper glitch--if you assign someone hopper just as he turns around from a wall, he will start hopping vertically up the wall and through any ceilings that may be present.

To use it here, have the first lemming shimmy near position shown in screenshot A.  He'll shimmy on the ceiling corner for a pixel or so and then turn around heading left.  Now apply hopper glitch to that lemming as he turns around at the left wall.

Just before he completely goes through, at position shown in screenshot C, assign him sand pourer.  This is to stop his hopping there, which allows him to continue going to the right--if you just let it naturally hop out, he will end up heading left instead.

Now get to the area below where the crowd is trapped and free them with the mortar.  It should be obvious how to do so with 1 slider, 2 glue pourers, and 1 mortar.

Polar 2: The two key ideas:

1) you can break through the floor using two well-placed flamethrowers.
2) you don't need the skater!  Due to a quirk with the way the ice works, each time a slipping lemming went back and forth once, he will actually drift slightly (maybe a pixel or so) in the direction he was facing before he began slipping.  So gradually he'll move off the ice if given enough time.

This leads directly to the 3-skill solution:  fence through the snowman, then after the lemmings turn around at the tree heading left, assign flamethrower at the positions shown in screenshots A and B (basically as far bottom and then to the right of the valley, and then same of the pit from the first flamethrower).

This will break through the floor, creating a path where all lemmings fall onto the ice facing left.  Now fast forward and wait.  The slipping lemmings will gradually drift left and will eventually exit.  The first one to exit is when the clock's around 1:40, and the last one around 0:14 (screenshot C).  The reason there's no 2-skill solution is because if the lemmings fall onto ice facing right, you'll run out of time long before many of them can exit.

Polar 5:  1st lemming out rope to the tree on the left immediately, as quickly as possible.  The 2nd lemming out will overtake him, but the idea is to have the 1st lemming out be following as close as possible to the 2nd lemming out.  Now, when the 2nd lemming out (now at the front) is close to the snowball left of the tree (screenshot A), assign him bomber.  The  1st lemming out (if you did the roping quickly so that he stays close) will overtake the 2nd lemming just as the explosion occur, causing him to the flung to the left, hit his head on the treeless island above, and turn faller (screenshot B).  The flinging and the lack of swooning will put him far ahead of the crowd (screenshot C).  Now just finish the rest of the path to the exit (screenshot D).  I've failed to find a way to do so in less than 6 skills.

Polar 3:  the screenshots tell you exactly where and how to rope to trigger crawling to the exit area.

Polar 9:  screenshot A shows you a spot you can build to seal off the left end of the starting platform without losing anyone.  Then jump a lemming up on the left to prepare the rest of the path to the exit.  Screenshots C-E show where to place the cannon, and where/how to rope to trigger crawling.  You'll also need to use the cannon pause trick (see geoo's reply #13) to ensure not runing out of time.

Shadow 8:  bash to the left at the bottom of the slope (screenshot A).  After the basher breaks through, a lemming will overtake him.  Just as that lemming starts to fall (screenshot B), assign the basher bazooka.  The timing of the knockback from the bazooka will knock the falling lemming into one of the pixel-sized protrusions off the column below and to the right (screenshot C), allowing him to platform from there to create a step to make the fall safe for everyone (screenshot D).  (The knockback also turns around nearby lemmings in the bash tunnel to ensure you have enough time to platform.)  The rest is obvious.

Shadow 10:  Assign 2nd lemming out SuperLem as soon as possible, and immediately pause.  Switch skill selector to builder, and when the 1st lemming out has past the middle of the smaller steel block, assign him builder (screenshot A) and pause immediately.  Move the mouse cursor all the way to the right past the 3 traps, to the upper-right corner of the steel block before the fall (screenshot B).  Unpause and wait for SuperLem to fly to the cursor and crash there (screenshot C), pausing immediately when the crash occurs.  Make the builder pour glue now, and then when a walker lemming is up on the glue platform and past the leftmost trap (screenshot D), make him pour glue too.  The resulting glue platform will span past all 3 traps.

Back to your former-SuperLem (aka hero), have him build at the very edge before the drop to water, and then as soon as the build brick is laid, have him pour glue.  As shown in screenshot E, most of the glue will span across the water-gap, and then there'll be just a little bit left over that will end up at the bottom of the right edge, creating a step to make the fall safe.

Make hero plant at exactly the position shown in screenshot E.  The plant will span the gap in question, and will also cause your hero to turn left immediately after planting, giving sufficient separation for him to build over the pit before the exit in time for the crowd (screenshot F).

[ccexplore]

Are you sure you can rule out the Tarzan route (which is amazing, btw) for Highland VIII just because of the time limit?  <snip>

Yeah, the time limit comment was just a rough guess based on how much time the Space VIII solution took, but then again I didn't really optimize that solution for time fully.  Execution will likely be the bigger pain point, as you noted with landing the lemmings in the basher tunnel.  I've also briefly tried it out and still haven't quite got the hang with handling the cannon, as you need to be careful with your pausing to maintain the correct firing frequency from the cannon, not to mention the need to move the cannon slightly to make it "skip" the first few lemmings while the hero's platforming.

Oh, and one more thing that I've tried and failed:  I was hoping I can swing a lemming sufficiently to the right so that when released, he's stuck inside the terrain and ends up crawling, making him face left instead of right, then re-catch him on the chain.  Unfortunately it doesn't work as the chain doesn't swing high enough to get the lemming stuck inside any terrain.

[edit: with regards to the above paragraph, I forgot to mention that you can actually catch lemmings on the chain facing right, if you position the cannon I think about 1 to 1.5 8-pixel block from leftmost position.  What would happen is that the flung lemming will get snagged at the left end of the terrain above the chain object, turning them into right-facing fallers which could then be caught by the chain.  But as noted in above paragraph, I'm unable to find any way to make one such lemming end up back on the chain again facing left instead of right, without using any skills.]

=========

Thanks also for looking at the Amiga version.  I didn't realize there are so many little differences here and there in the game mechanics!  Then again, I guess it's just like the little differences in Lemmings 1 DOS vs Amiga, only times 6 now that there are 51 skills instead of 8.

[LemSteven]

I've got a couple more improvements:

Beach 6 -- 6 (Yet another application of roper-induced crawling)
Beach 8 -- 6 (Avoids crowd control) EDIT:  Make that 5.  Apparently I didn't push my own method far enough.  Delaying the second lemming is not necessary, but getting an arrow fired quickly enough to save him is extremely hairy.

Edit:  I've got 11 skills for both classic 6 and Classic 9 10 skills for Classic 6 and 11 skills for classic 9.  Classic 6 is the standard solution, but Classic 9 requires a few precision moves (see below).

3/25 Edit:  Classic 2 is doable with 7 skills using at least two different methods.  I honestly don't know how I missed this earlier. http://www.lemmingsforums.com/Smileys/lemmings/tongue.gif" alt=":P" title="Tongue" class="smiley" />

Classic 6 is down to 10.  I'm still using the standard route, but I was able to manage the crowd more efficiently (and it's so simple that once again I can't believe I missed this earlier).

Beach 6:  Make the first lemming balloon over the tree, and then platform over the water.  Make him scoop as soon as he's to the right of the steel, and when he lands on the grass below, make him scoop again.  He should end up walking toward the trap under the exit.  From here, you're simply a roper-induced crawl away from the exit.  Finally, release the crowd by using a club basher through the tree.

Beach 8:  Give the first lemming a magic carpet as soon as he lands.  Use the fan to blow him down to the third of the three small floating islands below; he has to transform back to a walker as soon (i.e. as far to the left) as possible.  Immediately make him an archer and fire an arrow to the bottom right corner of the ledge that the crowd falls off of.  If you're quick enough, this arrow should arrive just in time to catch the next lemming as he falls.  The rest of the level requires two more archers and a builder, and should be self-explanatory.

Classic 9:  Make the second lemming build to slow him down.  The first lemming builds as close to the edge as possible.  The third lemming has to block on the first step of the first lemiming's bridge; place the cursor as low as possible to avoid selecting the builder.  The first lemming bashes the column and digs immediately after turning around at the wall.  Just before he runs out of stuff to dig, make him build; he should ultimately end up on the steel below.  Build over the water, climb the column, build to the next wall, and mine to reach the exit.  Finally, release the blocker with a miner.
(Note that I do believe stalling the second lemming is necessary; otherwise when he reaches the builder's first brick, the builder will still be on it.  This makes it impossible to avoid selecting the builder when assigning the blocker.)

[ccexplore]

Well I was going to post my results for Classics but it looks like LemSteven is getting to them now finally. http://www.lemmingsforums.com/Smileys/lemmings/tongue.gif" alt=":P" title="Tongue" class="smiley" />  I'll just say that I only found 3 levels with improvements, and all are simple miscellaneous improvements over a standard solution.  LemSteven just gave 2 of them as of this moment, I think I'll give him the chance to find the last one.

I was however able to improve my Sports 10 results down to 11 skills.  You can say I was inspired to take a second look partly after LemSteven's archery for Beach 8, and after much experimentation I finally got the archery to work in my favor (I had the basic idea before, but didn't think I can shoot the arrows fast enough/high enough/at a good enough angle to achieve full coverage of gap with this method.)  See attached screenshots (I re-included the old screenshots for the crawling part as well, which is why the skill counts for those 3 don't match with the other new screenshots.)  I think it's slightly more forgiving than Beach 8 but you should still try to be pixel-precise to the screenshots given.

[LemSteven]

Well I was going to post my results for Classics but it looks like LemSteven is getting to them now finally. http://www.lemmingsforums.com/Smileys/lemmings/tongue.gif" alt=":P" title="Tongue" class="smiley" />  I'll just say that I only found 3 levels with improvements, and all are simple miscellaneous improvements over a standard solution.  LemSteven just gave 2 of them as of this moment, I think I'll give him the chance to find the last one.

Okay, I was able to eliminate a digger from the beginning of Classic 8, bringing that total down to 10.  Was that the same thing you found?

[ccexplore]

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

Of course, don't let that stop you or anyone from looking at the Classic tribes or any of the other levels.  While I felt I've given all levels scrutiny at this point, I do and can miss stuff every now and then.

[geoo]

Yep, got Classic 8 down to 6 skills. I'm kinda surprised that you've overlooked that:

After blocking off at the start, bash into the wall, and when the basher is about to surpass the steel floor, have a lemming in front of the basher dig, however still close enough to the steel. If done correctly, the digger will remove two pixel layers and then stop, taking the basher down by two pixels which is barely sufficient to make the fall survivable. Build, bash and mine.

[ccexplore]

Good job! http://www.lemmingsforums.com/Smileys/lemmings/thumbsup.gif" alt=":thumbsup:" title="Thumbs Up" class="smiley" />  Didn't think of using the steel that way to stop digging.

Here's another improvement of one of my previous results:  Space 8 now down to 4 skills!  This came about directly from the "skills you can't live without" effort.  Still the Tarzan solution, only that it turns out you can just laser to release the trapped lemmings at the bottom and have all of them go left.  I've attached screenshots, and spoiler section below describes the timing details.

The key is that if you laser the bottom crowd as soon as possible, and laser as far to the left as allowed to break through, together with good timing you can have it so that no right-going lemmings are standing on where the laser breaks through when it does, so everyone can head left.  New incoming lemmings from the teleport automatically heads left, so you're set.

To do this in the Tarzan solution, as soon as you caught the first 2 lemmings on the chain, in the following right-swing, send 1 lemming to the gridwork--you need him to laser the upper-left group as soon as possible, since once you release the bottom group, you definitely do not want them wind up heading towards the chain.  Then continue fanning with the following left-swing and the following right-swing.  Now at the following left-swing, you will release a lemming to the left to laser the bottom group.  Timing is critical:  screenshot A shows the exact frame I released this lemming, and screeshot B shows the position I assigned him laser.  If all goes well, you'll get the result shown in screenshot C, where no lemmings head right when the laser breaks through.

================

This brings Space's new total to 53.  And speaking of 53, Shadow 10's current result is not "10?", and the total right now doesn't even match the numbers listed.  The correction should be 8 for Shadow 10, and a total of 53 for Shadow.

[ccexplore]

Thanks to my new discovery of a http://www.lemmingsforums.com/index.php?topic=199.msg8371#msg8371" class="bbc_link" target="_blank">glitch that lets walkers past the dragon harmlessly in Medieval 9, I now have a 3-skill solution for that level.

It's still important how you set it up though, because the dragon bypass glitch only works best when the lemmings are spaced the same as they come out of the entrance, so what you want is to have the runner hero alone handle everything that comes before.  Getting all that ready in time for the remaining lemmings can be slightly tricky even for a runner (though nothing new if you've seen my runners+archers solution for that level).  I've attached screenshots here for that.  Go to the post linked above for more details on the dragon glitch itself.