Turn the first lemming into a climber as he comes out of the trap door. Turn him into a bomber after he takes a few steps. Turn the next lemming into a climber as he falls and then a bomber a few steps further then the first bomber. Do the same with the third. Turn the last lemming into an athlete who will then float to the floor and walk to the exit. You will have to work on the timing to blow out a staggered path though the first two floors so the third lemming won't splat before he can blow up.
Immediately crank the release rate up to 80. Turn the first lemming from the right trap door into a digger just as he clears the overhang. The placement of this first lemming must be exact to allow a path for the left trap door lemmings and yet keep the right trap door lemmings from falling to their deaths. As the first lemming from the left trap door reaches the right wall of the hole, turn him into a digger also. These two holes should eventually merge together at the bottom. As each succeeding lemming from the right trap door steps out of the digger pit to the top of the wall, turn him into a digger as well. Soon you will have a growing slope of diggers. Have each lemming dig as wide a hole as possible or you will run out of lemmings. Sometime before the slope of diggers reaches the bottom, build a ramp off the bottom of the hole to keep the right trap door lemmings from falling too far. Once you have started a lemming digging the last bit of wall, sit back and relax. As each digger hits bottom, he will start marching up the slope and you will end up rescuing about 80%.
Set the cursor in the lemmings' path above the second rung from the left. Let the first lemming pass and turn the second into a digger. The third lemming will be trapped and eventually walk to the left over the first rung. Turn him into a digger just as he gets over it so that he is trapped in the rung. When the first lemming reaches the ball, have him dig down the vertical shaft. Make sure that a slice of the pole remains on the left to keep this lemming separated from the rest. As each of the rest of the lemmings reach a rightmost empty rung, have them dig into it. Eventually you will have 18 lemmings, each trapped in his own rung. Have the last lemming dig right above the double icicle. Then have this lemming build the bridge over the gap and then bash though the ice crystals to the exit. Starting from the rightmost rung, have each of the lemming dig through the spike under the rung. Be very careful that you do not damage the neighboring rung or that lemming will fall to his death. The isolated lemming on the right must start bashing to the left with at least 2:30 minutes left on the clock for everyone to reach safety in time.
Turn the first lemming into a floater. Turn the next into a blocker after he has taken a step or two. Have the first lemming build against one of the low steps to turn him to the left. Near the left side have him build a ramp to the lowest block. He will hit the block and head back to the right. Turn him back to the left by building against another step. At the top of the lowest block, build to the next block. He will hit the block and head back to the right. Halfway down the ramp start building to the rightmost block. Halfway back down that ramp start building to the upper leftmost block. As soon as he bounces off that block, start building toward the exit. You should have one or two builders left when you are finished. After the ramp is complete, bash out the left wall and allow the rest of the lemmings onto the ramp. Turn one of the fallers from the trap door into a digger as soon as he hits the ledge which will free the blocker. Turn the blocker into a digger as soon as he is free. When the blocker falls to the block below, turn him into a builder so that he will hit his head and turn around. Crank up the release rate to 99 and the rest will fall through to the ramp and head to the exit.
Turn the first lemming into a climber. As soon as he reaches the top turn him into a digger. Make him dig as narrow a gap as possible. When he reaches the region between the one-way layers, turn him into a basher. Just before he reaches the end of the block, turn a faller from the trap door into a climber. Both climbers should end up climbing the rightmost wall. Turn the first climber into a builder to close the gap between the rightmost wall and the ledge protruding from the one-way block. The second climber should have just passed the first before he started building. After the first climber gets on the ledge, turn him into a miner. Start the second climber building over the first climber's hole. Have the second climber also build the ramp to the exit. Now create a third climber from one of the milling lemmings below. As the first climber finishes the top half of the mine, have him start on the second mine. Have the third climber build a ramp between the two mined sections. The rest of the lemmings should march up the mined sections and then along the top to the exit.