Free 32/64/16-bit multi-platform Pascal and Object Pascal compiler
A 32/64/16-bit Pascal compiler for Win32/64/CE, Linux, Mac OS X/iOS, FreeBSD, OS/2, Game Boy Advance, Nintendo NDS and DOS; semantically compatible with Delphi, Borland Pascal and Mac Pascal (partially) with extra features, e.g. operator overloading.
Versatile Commodore Emulator
VICE is an emulator collection which emulates the C64, the C64-DTV, the C128, the VIC20, practically all PET models, the PLUS4 and the CBM-II (aka C610). It runs on Unix, MS-DOS, Win32, OS/2, Acorn RISC OS, BeOS, QNX 6.x, Amiga, GP2X or Mac OS X machines.
Hammer of Thyrion (uHexen2) is a cross-platform port of Raven Software's Hexen II source. It is based on an older linux port, Anvil of Thyrion. HoT includes countless bug fixes, improved music, sound and video modes, opengl improvements, support for many operating systems and architectures, and documentation among many others.
A cross-platform interpreter for many point-and-click adventure games
ScummVM is a cross-platform interpreter for many point-and-click adventure games. This includes LucasArts SCUMM games (such as Monkey Island 1-3, Day of the Tentacle, Sam & Max, ...), many of Sierra's AGI and SCI games (such as King's Quest 1-6, Space Quest 1-5, ...), Discworld 1 and 2, Simon the Sorcerer 1 and 2, Beneath A Steel Sky, Lure of the Temptress, Broken Sword 1 and 2, Flight of the Amazon Queen, Gobliiins 1-3, The Legend of Kyrandia 1-3, many of Humongous Entertainment's children's SCUMM games (including Freddi Fish and Putt Putt games) and many more. The project mailing lists have been moved to http://lists.scummvm.org The project tracker has been moved to https://bugs.scummvm.org
Old style soccer game with many exciting features
Eat the whistle GPL is a football simulation game written in C that works on many platforms (win32/linux/macosx/amigaos/morphos), it uses the SDL framework. It has a multiplayer internet playing option in alpha stage.