Trigger Rally is "a fast-paced single-player racing game for Linux" and now, thanks to WebGL, Three.JS, and Jasmine Kent, everyone can play in a browser.
posted by mrgrimm on Mar 2, 2012 - 17 comments

Here is VASSAL, an open-source engine for playing board games online, by email, on forums or on a single machine. Which board games? These. (Requires Java.)
posted by JHarris on Dec 7, 2011 - 41 comments

id Software have released the source code to Doom 3 under the terms of the General Public License. [more inside]
posted by smcg on Nov 30, 2011 - 24 comments

Open Tyrian OpenTyrian is a port of the DOS shoot-em-up Tyrian (previously). The port uses SDL, making it easily cross-platform. Builds are available for Windows and Mac OS X [... and] for Android, Amiga, Dingoo, Dreamcast, DS, GameCube, Gizmondo, GP2X, GP32, Nokia Internet Tablets, PSP, PS3 Linux, Symbian, Wii, and Wiz
posted by kid ichorous on Jan 8, 2011 - 21 comments

Raising for Ryzom. Saga Of Ryzom's parent company is having some sort of undisclosed trouble, and a group of users are raising funds to purchase the source code and art assets. So far, they've raised 60k in euros.
posted by ®@ on Dec 1, 2006 - 3 comments

ChessRogue = Chess + Rogue. (Open source, versions available for Linux and Windows.)

This console-based game takes the pieces of chess and puts them into a Roguelike environment. You start out with a weakened King who can only move and capture horizontally and vertically, in a randomized board full of multi-directional Pawns. As you capture more pieces, the king slowly gains additional powers, like diagonal capture and movement, Knight jumping, and eventually even Rook movement, among others. The opposition gets tougher too, until eventually the entire selection of pieces is out to get you.
Originally created for a three-day programming challenge on rec.games.roguelike.development, it's surprisingly cool, and works rather better than you might expect. It's useful as a break between Nethack fatalities.
posted by JHarris on Aug 2, 2005 - 19 comments