Pingus

Description
Pingus is an open source, cross-platform, and free Lemmings clone. The gameplay is the same: the player must help a group of creatures (in this case, penguins) to reach the exit and escape the level.
Each penguin has to be assigned a task, represented by a series of icons at the left side of the screen. Blockers stop the other penguins, and are best deployed near dangerous environments and chasms. Jumpers spring upwards, arcing through the air, covering a small distance. Bridgers build diagonal bridges across chasms. Bombers explode, removing a chunk of the terrain with them. Diggers go downwards, mining deep in the ground, or sideways, tunnelling through walls. Sliders lunge forward, passing under low roofs and escaping some traps. Climbers have the reusable ability to scale vertical walls, and floaters have the reusable ability to survive any fall.
As in the original, each level has a set number of penguins that have to cross the portal (sometimes with a time limit). Three icons at the bottom pause the game, make it run faster, or explode all the birds (useful if the level was made unsolvable by wrong actions).
The game has a built-in level editor, that can be accessed directly from the main menu. Extra unofficial levels can be found in several sites.