Nexuiz is a first-person shooter by Alientrap Software. It is a free game: source code is free software and data is free content.

Nexuiz is a FPS with nine weapons, 24 official maps and over 240 community created maps, as well as 15 player models.

Nexuiz is primarily multiplayer (though it includes a full single-player campaign, which allows one to play through the various multiplayer game types and maps with bots), and allows for hosting and joining of games. It can also support new gametypes, or whole conversions quickly applied to it (much like Quake). Nexuiz supports most Quake modifications (although with varying functionality).