Stealth game is a video game genre in which the player must avoid detection, using stealth to evade or ambush antagonists. Games in the genre employ mechanics such as hiding in shade, disguises, and noise which can alert enemies. Some games allow the player to choose between a stealthy approach or directly attacking antagonists, perhaps rewarding the player for greater levels of stealth. The genre has employed espionage and counter-terrorism themes, with such protagonists as special forces operatives, spies, and ninjas. Some games have employed stealth game elements with those of other genres, such as first-person shooters or platform games.