"Unreal Tournament 2003 or UT2003 is a first-person shooter video game designed mainly for multiplayer gaming. The game is part of the Unreal franchise's series of games, and is a sequel to Unreal Tournament (UT99).
The game set a record for the number of downloads (1.2 million) when the demo was released, which is a reflection of the popularity of the original UT. In addition, the game engine has been widely licensed for games such as the Tom Clancy's Rainbow Six series, Splinter Cell, and America's Army.
Unreal II: The Awakening was released as a sister product to the game."
Source: Wikipedia, "Unreal_Tournament_2003," available under the CC-BY-SA License.