Emulator of Atari 800/800XL/130XE/5200 with various extensions (1088kB RAM, stereo sound and much more) running on just about every operating system (Unix/Linux, Windows, DOS, TOS, MacOS, Workbench, WinCE...)
An open-source Phantasy Star Online server for *nix
Sylverant is an open-source server for the Phantasy Star Online series of games by Sega, written primarily for Unix-like operating systems. Sylverant has at least partial support for most versions of Phantasy Star Online, from the Network Trial for the Dreamcast through Blue Burst for Windows.
Open Source Video Games for; Android, Desktop etc.
Open Source Video Games developed by MetalManGames team for; Android, Desktop etc. Under the BSD clause-3 license.
A fast, unobtrusive and modern cross-platform GUI toolkit. Agar fully exploits hardware acceleration where available, but also supports simple frame-buffer interfaces. Agar is stand-alone and easily portable to new platforms and graphics systems.
Text-based adventure game
Text-based adventure game; can you find enough magic rings and incriminating documents to indict and retire all the politicians before your HP runs out?