enelin8 is a sci-fi 3d shooter. You receive a cryptic distress call from the moon Beya B4, normally inhabited only by robotic mining drones. Upon setting out to investigate, the drones attack you. Blast your way through walls and defenses with your well-armed shuttle, deeper down into the robotic mining facility towards the source of the distress signal.
Adanaxis is an action game where the fundamentals of space itself are changed by adding a fourth dimension to space. Initially, it's like learning to play a 3D FPS for the first time, as the hand and eye have to learn a whole new type of coordination. The gameplay involves rapidly blowing things out of the sky, with the usual assortment of enemies, allies, weapons, and power-ups, together with commercially sourced graphics, audio, and voice acting.
EDM is a fork of Sauerbraten (http://www.sauerbraten.org/) which is in development but playable. It features several multiplayer game modes like Deathmatch and Instagib, dynamic map model physics, enhanced particle effects, unique weapons and powerups, and more. Maps can be edited with other players online.
Excalibur: Morgana's Revenge (EMR) is a first-person shooter game with an epic and in-depth story line. The player travels through time in the Jurassic period, Camelot period, and into the future to chase down Morgana. Using the Aleph One engine, EMR creates an amazing new world, making it an entirely fun and unique gaming experience.
Crystal Core is a FPS quest-based game written with Crystal Space and Crystal Entity Layer. The game is based on a science fiction story. The player and his or her companions crash on an alien planet where they discover that the original intelligent inhabitants are now extinct due to an invasion of semi- primitive aliens from a distant planet. Your goal is either to destroy all aliens or escape the planet alive. To accomplish these goals you have to use alien technology and try to interface it with the broken ship that you arrived with.
Sauerbraten (a.k.a. Cube 2) is a free multiplayer/single player first person shooter, built as a major redesign of the Cube FPS. Much like the original Cube, the aim of this game is not necessarily to produce the most features and eye candy possible, but rather to allow map/geometry editing to be done dynamically in-game, to create fun gameplay and an elegant engine.
The Castle is a first-person shooter game in a dark fantasy setting. Your main weapon is a sword, so the fight is mostly short-range. Three main levels are included, packed with creatures, items, and sounds. A couple of bonus levels are also available, like the classic DOOM E1M1 level reimplemented in VRML. The game engine is based on VRML, OpenGL, OpenAL, and all shadows are done by the shadow volumes approach.