Xxxxxx is a plot-driven first-person shooter that uses the Doom engine. Rather than taking the player through a linear series of levels, the game offers a continuous world with free-roaming elements and a central "hub" (the town), which the player can visit between missions and explore. Although there are no true role-playing elements in the game, it has several features rarely seen in contemporary FPSs: there are "friendly" areas where there are no enemies but people to talk to, stores where new equipment can be bought, and taverns where the latest gossip is told. The player can also purchase upgrades that permanently increase the player character's health bar.
The game has a branching storyline with a few paths that lead to three different endings. These paths are determined by a decision the player makes during the course of the plot.