ANOTHER WORLD / FoxySofts / Gameboy Advance
This Gameboy Advance port of Another World (aka "Out of This World" in the United States) was apparently created by FoxySofts as a side project while the mobile phone version of this game was being experimented with, and it's been released to the public as freeware with the blessing of original creator Eric Chahi.
This version is a port of the Atari ST version of the game, which was the first port made after the game was originally released in its first incarnation on the Amiga. What this means is that those who may have played later versions, like the Super NES and MS-DOS ports, will notice some things are missing. There was an extra level added for those games that is not present in this version, and the revamped musical score of the Super NES version is also not present in this one. What you *do* get, however, is a very zippy version of the game that runs rings around the console ports. It also lacks the censorship that was in some of the later versions - blood, grim cutscenes and naked alien babes ahoy!
And hey ... it's free. Plus, if you use a good Gameboy Advance emulator such as Virtual Boy Advance, you can take advantage of saved states to ease up some of the trickier bits, and you can also use the USB gamepad or joystick of your choosing.