Free/Open-source First-person Shooter Games
A first-person shooter (Commonly called FPS) is an action video game that involves "an avatar, one or more ranged weapons, and a varying number of enemies". FPSs render the game world from the visual perspective of the player character. FPS was one of the first genres to use key technologies such as 3D graphics, online play, and modding. Enhanced realism combined with graphic violence has also made FPS a common topic in ongoing controversies over video games.
I have collected some quality free/open-source first-person shooter games. Just a little warning to parents though; most of these games are indeed violent. You better let your little kids sleep first before splurging with these games. So without any more delay, here's the list already:
*AssaultCube, formerly ActionCube sets in a realistic looking environment, as far as that´s possible with this engine, while gameplay stays fast and arcade. This game is all about team oriented multiplayer fun. Although, a single player mode exists which consists of computer-controlled bots. It also includes Cube's map maker which allows for in-game editing.