To start off, Xonotic offers no less than sixteen different play modes, including, of course, the classic capture the flag or the legendary individual or team 'deathmatch'. In addition, as it is in some way geared towards competitive play, Xonotic has a number of play modes that are especially geared towards one on one duels.
The main characteristic of Xonotic, and one that definitely does not make it any different from the rest of the games in this genre, is its speed. The game not only allows you to practically fly through the scenes, but it also almost pushes you to do so. All of the traditional techniques that allow you to move quickly in these kinds of games are here: 'strafe jumping', 'rocket jumping', etc.
The mix of this speed of travel, plus a scene design that favors it, could make even people with the strongest stomachs motion sick.
Xonotic is a fun 'online' shooter. Even though it's geared towards competition, it also has play modes for those who just want to enjoy a few battles against other players.