This puzzle game by Scottish studio DMA Design takes as its inspiration the myth that
lemmings (arctic rodents) mindlessly fling themselves off cliffs. In the game, lemmings (pixelly humanoids with green hair and blue leotards) fall from a trap door and begin marching mindlessly to the right, oblivious to cliffs, fire, lakes of acid, and other deadly hazards. When they hit a wall, they turn 180 and march the other way. It's your job to guide as many of them as possible safely to the exit.

To accomplish this, you can assign individual lemmings one of eight skills: Climber (climbs vertical walls), Floater (uses an umbrella to survive falls), Bomber (explodes after 5 seconds, leaving a crater), Blocker (stands in place and won't let other lemmings past), Builder (builds a staircase), Basher (digs a horizontal tunnel), Miner (digs a diagonal tunnel), and Digger (digs a vertical tunnel). Each level offers a limited number of skill assignments, so you have to use them strategically to create a path for the others.
Lemmings was wildly popular in the '90s, spawning multiple expansion packs, sequels, and spinoffs. As a child I don't know if I was really aware of what a global phenomenon it was, but it was certainly a phenomenon in my house, considering the countless hours my brother and I spent trying (and usually failing) to stop the cute little dummies from marching to their doom.
( cut for length )The original Lemmings is unfortunately not commercially available. If you've misplaced your floppies/cartridge,
various releases are available as abandonware. I was playing the DOS release on
DOSBox, which runs fine but you may need to
edit some files to defeat the copy protection. If that doesn't sit well or sounds like too much trouble, there are also
several fan-made freeware clones that are supposed to run on modern systems, though I have not personally vetted any of them.