Oh No! It's the 4TH DIMENSION!
Number of lemmings that drop: 50
60% to be saved
Release rate: 1
Available time: 04:00
Just ignore the lower-left entrance, you save enough lemmings. The first lemming at the lower-right entrance builds over the gap and back up to the gray stairs. Turn two lemmings at the upper-left entrance into a bomber. Let the one lemming build over the exit twice so he can bash through the one-way obstacle.
-= Another solution from Daniel Normington =-
I notice the solution given here says, "Just ignore the lower-left entrance, you save enough lemmings."
This is probably true enough, but I (a) don't really like to take chances and (b) like to save every one I can... anyway, I find I have plenty enough builders to let them build up and over the traps to reach where the lemmings enter at the lower-right, while still working to save the others.
Last edit: Wednesday, 14 May 2008.
Main source: own words.
Graphics: Oh no! More Lemmings, Amiga platform.