Pingus

Pingus is a free and open source Lemmings clone which also incorporates other elements (such as the worldmap) from Super Mario games and introduces some new elements (such as the Jumper.) Instead of lemmings, you control penguins, known in-game as "Pingus", as they embark on a journey to find out why the South Pole's ice is melting. The main story mode only contains one worldmap: the Island of Mogorok, also known as the Tutorial Island. However, there are additional levelsets included in the game meant to continue the story, and the user can make their own levels with the level editor.

This game is not to be confused with a show about a certain claymation penguin or a meme based on Adventures of Sonic the Hedgehog.

The game's official website can be found here, where it is available to download for Linux distributions, Mac OS X, and Windows.

Tropes used in Pingus include:

Christmas Episode: The "Xmas 2011" levelset.
Everything's Better with Penguins: Kind of goes without saying, doesn't it?
Family-Unfriendly Death: The Pingus can die in some pretty gruesome ways, such as by drowning, exploding, getting squashed by a hammer, and falling from great heights. Though the deaths are arguably not as shocking as those seen in Lemmings, they can still be rather grim to see unfold.
Halloween Episode: There are two Halloween levelsets included in the game: "Halloween 2007" and "Halloween 2011".
Justified Tutorial: The Tutorial Island is established in the game's story to be a place of preparation for adventuring Pingus whenever they go out into the world.
Public Domain Soundtrack: Similar to its inspiration Lemmings, this game includes some songs based on common tunes.
- The "Halloween 2007" and "Halloween 2011" levelsets feature a track based largely on Grieg's "In the Hall of the Mountain King" (though it is mistakenly labeled as "The Sorcerer's Apprentice" in the music file's metadata; additionally, the file is named "sorcerer.it".) However, the track itself is derived from a track used in Manic Miner, specifically a freeware remake made in 1997 by Andy Noble.
- The "Factory" levelset features a version of Offenbach's "Can-Can".
- An unused alternate level completion theme is an adaptation of "For He's a Jolly Good Fellow".
Shout-Out: It has been stated that the penguins are a reference to Tux, the Linux mascot.
- There's also the level "Pingu Jones and the Last Exit" in the "Desert" levelset.