The player controls Wade Wilson (a.k.a. Deadpool), a loud-mouthed, foul-mouthed merc with a mouth. While on a contract to assassinate a corrupt media mogul, Mister Sinister intervenes and kills him instead, infuriating Deadpool, who vows vengeance only to discover a larger scheme that could herald the end of humanity. They get together to stop Mister Sinister and his squad of Marauders (Arclight, Blockbuster, and Vertigo) from succeeding, with the help of some X-Men, such as Wolverine, Rogue, and Domino, as well as a friend from the future, Cable.
True to his nature, Deadpool repeatedly breaches the fourth wall throughout the game, even though he begins by using “explosive persuasion” on executives at developer High Moon Studios to get him into a game. As a result, he refers to the game’s script, remarks on specific achievements/trophies, addresses the player, and even mocks the player if he performs poorly during the game. It also references many franchises (such as Transformers and Spider-Man) and video games (The Legend of Zelda).
The main gameplay is a third-person slash fest with guns, with Deadpool beginning with his iconic Katanas and duel pistols. As the game advances, the player can upgrade Deadpool and purchase new guns and melee weapons by utilizing DP (Deadpool Points) collected from adversaries defeated and dispersed across the stages. The player can chain combos together to gain more DP by successfully hitting and shooting adversaries; the higher the combo, the more points the player receives. Momentum is also gained during these combos, which, when activated, can wipe out big groups of foes or collect tacos dropped by enemies.
Like X-Men Origins: Wolverine, Deadpool can restore his health and employ teleport to slip behind foes and counter their incoming strikes. While there is no multiplayer mode, there is a challenge mode in which players can go to arenas unlocked during the story and fight against wave after wave of foes to climb the scoreboard.