Ecks vs. Sever is a first-person shooter based on the 2002 movie starring Lucy Liu and Antonio Banderas, which hadn't yet begun filming at the time of the game's release. You take on the role of either male ex-FBI agent Johnathon Ecks or the female assassin known only as Sever, as each tries to survive the other, as well as a possible government conspiracy. Although each of the characters' 12 missions follows the same storyline, you encounter events from their perspective, and your goals change accordingly. The plot is forwarded through text-based cut-scenes after each level. Ten weapons are at your disposal, ranging from a pistol to a grenade launcher to a G11 assault rifle.
In addition to the single-player game, two to four players can compete in one of three multiplayer modes. Besides the self-explanatory Deathmatch, there's Bomb Kit, in which players try to assemble three parts of a bomb, and Assassination, in which one player tries to kill a CPU-controlled "VIP," while the others try to stop him/her.