Battle for Wesnoth - - Polished turn based strategy game featuring fantasy characters and modular plots.
Cedega - - Commercial re-implementation of the Windows API for Linux with a focus on gaming. Similar to (and a derivative of) WINE.
comisat Games Collection - - GPL licensed multiple game package featuring classic game remakes including Connect4 and Tetris.
Defendguin - - New Breed Software's clone of the Williams arcade classic "Defender." Instead of humanoids, you rescue penguinoids.
D2X-XL - - Aims to create a better Descent 2 in OpenGL. Maps, levels, and sourcecode are available.
Gamma Patrol - - Old-style vertical scrolling space-shooter. Fight your way through enemies using different weapons.
Gem Drop X - - Fast-paced puzzle game where it's your job to clear the screen of gems before they squash you.
GTK Cervi - - Clone of the game called Cervi (Worm). It is a multiplayer game (on one machine) where players drive worms and mustn`t collide with anything.
gtkmonop - - GTK+ client to monopd. Monopd is a daemon for playing monopoly over the Internet.
Lost Labyrinth - - Modern graphical rogue-like game. Currently in a release state, it is also under constant revision. Source available.
NERO - - Game and engine that revolve around "training" AI robots to engage on a futuristic field of battle.
OpenCity - - Free 3d city simulator written from scratch using OpenGL and SDL.
Powermanga Linux - - Arcade 2D shoot-em-up game with 41 levels and more than 200 sprites.
Vega Strike - - Elite like space sim and game engine with modern rendering and capabilities.
WINE - - Not directly a game, but a set of APIs that can be used to port Windows games to Linux or to run them directly.
WorldForge Project - - Aims to produce an immersive environment engine for high quality games. It is both a community and a game engine with game implementations already finished.
XArchon - - Play-alike of Archon which was created by FreeFall Associates and distributed by EA.
XFrisk - - Networked X11R6 (Unix GUI) "Risk" like boardgam.