Bitfighter is a game that feels a little like Asteroids on steroids. It's a multiplayer space-based combat and strategy game, featuring customized ships, multiple game modes, cool retro graphics, and smooth network play. It also includes a full featured level editor, Lua scriptable bots, and other cool features. It has a very active development team, so the game keeps improving.
BOH is a unique retro-flavoured puzzle-riddled maze game. The player moves in claustrophobic, mysterious, dangerous battlefields searching for the Evil Masters, who throw countless enemies at you until you discover and face them in the final battle. Although quests are made slightly less hard by the power-ups scattered all around, carrying out the missions demands lots of concentration and quick reflexes. New missions and themes can be added anytime, and you can even create your own.
Gigalomania is a 2D real time strategy game that is a clone of Mega-Lo-Mania. The gameplay consists of researching and developing new technology with which to conquer your enemies, from rocks and sticks to nuclear weapons and spaceships. You can advance through ten different ages, from the stone age to the future. There are 28 different maps to play through. The game is still under development, but is entirely playable in its current state.
Arx Libertatis is a cross-platform, open source port of Arx Fatalis, a 2002 first-person role-playing game developed by Arkane Studios. Arx Fatalis features crafting, melee and ranged combat, and a unique casting system where the player draws runes in real time to effect the desired spell. The Arx Libertatis source code is based on the publicly released Arx Fatalis sources. This does however not include the game data, so you need to obtain a copy of the original Arx Fatalis or its demo.