Tremulous is a shooter game released in 2006 designed and developed by Dark Legion Development. Tremulous can be described as a free, open source game and can be played on the following operating systems: Windows, Linux, Mac OSX, Amiga. Tremulous is also a multiplayer game.
“Tremulous is a free, open source game that blends a team based FPS with elements of an RTS. Players can choose from 2 unique races, aliens and humans. Players on both teams are able to build working structures in-game like an RTS. These structures provide many functions, the most important being spawning. The designated builders must ensure there are spawn structures or other players will not be able to rejoin the game after death. Other structures provide automated base defense (to some degree), healing functions and much more...” - Dark Legion Development