Tremulous

Gameplay
Tremulous is a first-person shooter with elements of real time strategy. Each team must construct and defend a base, consisting of structures which aid the players in some way. The most important structure is the spawn, which provides each team with reinforcements to replace players who have been killed.

During a match, most players engage in fighting the enemy, while others maintain the base and construct new structures. In order to destroy the enemy, humans utilize various weapons, armor and other upgrades, while aliens may evolve into more powerful classes, each of which possesses unique abilities.

The teams do not have access to all possible upgrades and buildings at the beginning of the game. Each team must reach a threshold of frags 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. The aliens are awarded frags for killing their foes which may be used to evolve (these points are commonly called evos by players). The Humans gain credits. Players earn currency by killing enemy players or by destroying key enemy structures; the amount of received currency depends on what class the opponent was (or what 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 currency every two minutes by simply staying alive.

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.

Aliens


The alien base is centered around a structure called the "Overmind", which is needed for their other structures to function and new structures to be built.

Aliens spawn from Eggs. Eggs work even when the Overmind is dead, but new eggs cannot be built without it.

As they earn frags, alien players can evolve into a new form in order to upgrade their health and gain new abilities. As the vast majority of alien attacks are melee attacks, most of these creatures depend on agility and special movement techniques such as wall-walk, wall-bounce, charging and pouncing over long distances to close the distance between themselves and their enemy.

Humans


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. At the core of the human base is the "Reactor", responsible for powering nearly all other base equipment. If it is deconstructed or destroyed, automated defenses and upgrade structures are rendered useless; if it not immediately replaced the human team is usually defeated.

Development
Tremulous' development commenced in early 2000 as a modification for the commercial computer game Quake III Arena. The gameplay is generally inspired by the Quake II modification Gloom, although they share no content.. Version 1.0.0 was released on August 11, 2005. Because it was released after most other Quake III Arena mods, it was initially overlooked by many.

Though Tremulous features a similar theme and game-play to Natural Selection, the developers say it is neither based on it nor inspired by it. Development on the game began "long before NS was in the public domain". The similarity in gameplay can likely be accounted for by the fact that the Tremulous team cite an earlier game as a possible inspiration, a Quake 2 mod called Gloom. Gloom may have had a similar impact on the development of Natural Selection.

Following the release of the Quake III Arena source code under the GPL on August 19, 2005, the developers decided to rework Tremulous into a standalone, free and open source game. The current stable version, 1.1.0, was released on March 31, 2006 and is based upon ioquake3, a modified id Tech 3 engine. This version was better received than previous versions and attracted a considerable following in comparison to its peers.

The latest version is 1.2 beta "Gameplay Preview". It was released on December 4, 2009 and is currently undergoing community testing and review. It has introduced a large number of gameplay as well as server and client changes and upgrades. The community is still somewhat divided over them.

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 and Linux, and an unofficial client for Mac OS X(for version 1.1). An official client is available for 1.2 Beta for Mac. The release of the game as free and open source software allows programmers to modify the game. 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. Tony J. White (tjw), a key developer of the ETPub mod for Wolfenstein: Enemy Territory, contributed an administrative system and a backported client that were soon incorporated into the official Subversion repository.

Reception
Joe Barr of NewsForge considered Tremulous to be one of the best free first-person shooters.

Tremulous later came in first in a "Best free game based on GPL Quake source?" poll on the Planet Quake 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(formerly Computer Gaming World): 101 Free Games Issue for 2007.

Modifications
The Quake 3 engine allows easy creation of platform-independent mods, a feature naturally inherited by Tremulous. In addition, its basis in the GPL requires and encourages the community to share the code of binaries they distribute. As a consequence, several mods have been developed and released, and many patches and custom builds have arisen. In addition to client-side mods, server modifications allow settings be manipulated without requiring clients to download any supporting files.