Very fast and versatile 3D modeller/renderer

blender

Very fast and versatile 3D modeller/renderer

Blender is an integrated 3d suite for modelling, animation, rendering, post-production, interactive creation and playback (games). Blender has its own particular user interface, which is implemented entirely in OpenGL and designed with speed in mind. Python bindings are available for scripting; import/export features for popular file formats like 3D Studio and Wavefront Obj are implemented as scripts by the community. Stills, animations, models for games or other third party engines and interactive content in the form of a standalone binary are common products of Blender use.
Go client and full featured SGF editor

qgo

Go client and full featured SGF editor

qGo is a computerized board on which you can play the game of Go against another player, view and edit smart-go files, and connect to Go servers on the internet. It can also interface with computer Go programs such as GNU Go that speak the Go modem protocol. Have a look at the cgoban package if you are interested in a Go client with less package dependencies.
fast-paced 3D first-person shooter

openarena

fast-paced 3D first-person shooter

OpenArena is an open-source content package for ioQuake3 licensed under the GPL, effectively creating a free stand-alone game. Though OpenArena is a free replacement for id Software Inc.'s Quake 3 Arena, it is NOT compatible with the proprietary game!
The GNU Bombing utility

bombardier

The GNU Bombing utility

This game is the same as the old Blitz16 game on Commodore 16/Plus 4, written by Simon Taylor.
free Bomberman clone

bomberclone

free Bomberman clone

BomberClone is a free Bomberman-like game for Linux and Windows. The rules of the game are simple: run through a level and bomb other players. It features powerups that give you more strength, make you walk faster through the level, or let you drop more bombs.
Client for the multiplayer roguelike Crossfire

crossfire-client

Client for the multiplayer roguelike Crossfire

Crossfire is a free, open-source, cooperative multi-player RPG and adventure game. Since its initial release, Crossfire has grown to encompass over 150 monsters, 3000 areas to explore, an elaborate magic system, 13 races, 15 character classes, and many powerful artifacts scattered far and wide. Set in a fantastical medieval world, it blends the style of Gauntlet, NetHack, Moria, and Angband.