It was released on March 31, 2006. The game features two teams, humans and aliens, each having to build and protect a base. Victory is achieved by the destruction of the enemy base and by eliminating all members of the enemy team. The game has been downloaded over 1,000,000 times and was voted Player's Choice Standalone Game of the Year in Mod Database's Mod of the Year 2006 competition.
Tremulous is a first-person shooter with elements of real time strategy, featuring two teams - humans and aliens. Players must build and protect a base which is essential for their survival, consisting of working buildable structures which provide various functions, the most important of which being the ability to respawn. Victory is achieved by destroying all enemy spawn points and eliminating all members of the enemy team.
During a match, most players engage in fighting the enemy, while others are responsible for base maintenance and construction of new structures. In order to defeat the enemy, humans utilize various weapons, armor and other upgrades, while aliens may evolve into more powerful classes, each possessing unique abilities.
The teams do not have access to all possible upgrades and buildings at the beginning of the game. Each team must accrue a number of kills in order to advance to the next developmental stage. The point at which a stage change occurs varies dynamically depending on the number of players on each team. Each new stage brings more upgrades for the humans and more classes for the aliens.
In addition to requiring a certain stage, each human item or alien class must be purchased using currency earned in game. Alien currency are officially called frags, although players frequently refer to them as evolution points or evos. The Humans gain credits. Players earn currency by killing enemy players or by destroying key enemy structures. Amount of received currency depends on how upgraded the opponent was (or which structure was destroyed) and how much of the target's total damage was dealt by the killing player. As a mechanism to encourage builders, who naturally don't engage in combat, players are also rewarded by currency by simply staying alive for certain amount of time.
Builders are responsible for construction of new buildings and base maintenance. Each building takes up a certain number of build points available to each team. The number of build points can vary from map to map and server to server, limiting how large bases can become. To reduce the likelihood of the match ending in a tie, most games enter a sudden death mode ten to fifteen minutes before the draw/tie time limit. This is a period during which the building of most or all structures is prohibited, allowing attackers to more easily overwhelm the defenders.
The alien base is centered around a building called the "Overmind", without which many of their other buildings do not function, and they spawn from Eggs. Aliens evolve into a new form in order to upgrade their abilities, most of which have only melee attacks.
Humans utilize various weapons, armors and other high-tech equipment as a means to augment their combat abilities. They are primarily suited for ranged fighting and need a strong, defensible base in order to survive. They can save up to 2000 credits for purchasing upgrades at the armory, which range from 70 to 600 credits in price.
Tremulous's development commenced in early 2000 as a modification for the commercial computer game Quake III Arena. The game-play is generally inspired by the Quake II modification Gloom, although they share no content. . Version 1.0.0 was released on August 11th 2005. Because it was released after most other Quake III Arena mods, it was initially overlooked by many.
Following the release of the Quake III Arena source code under the GPL on August 19th 2005, the developers decided to rework Tremulous into a stand alone, free and open source game. The current version, 1.1.0, was released on March 31st, 2006 and is based upon the ioquake3 Quake III source port. This version was received much more positively than those previous and attracted a considerable following in comparison to its peers.
Tremulous is licensed under the GPL, although it includes code from other projects that was released under other GPL-compatible licenses. Most of the game media is licensed under the Creative Commons Attribution-ShareAlike 2.5 License.
There are clients for playing Tremulous available for (Windows, Linux and Mac OS X). The release of the game as free and open source software allowed programmers to modify the game and game engine. A growing number of players are releasing patches for the game in order to remove bugs, add features to the game or modify the game play itself. Tony J. White (TJW), a key developer of the ETPub mod for Wolfenstein: Enemy Territory and current developer of Tremulous's administrative system (used by server administrators), released a widely used patch for Tremulous. The majority of his modifications are slated to appear in the next official release.
Tremulous later came in first in a "Best free game based on GPL Quake source?" poll on the PlanetQuake website. At the beginning of 2007, Tremulous also took first place in the Mod Database "Mod of the Year" 2006 competition under the category of "Player's Choice Standalone Game of the Year" as well as honorable mentions in "Genre Award: Action" and "Editor's Choice Standalone Game of the Year". Tremulous was also mentioned in Games for Windows: 101 Free Games Issue for 2007, Games for Windows formerly being Computer Gaming World.
The Quake 3 engine has good support for modding and this feature is inherently available in Tremulous. In addition, code for Tremulous is available to the public. For these reasons, a modding community has developed around the game.