This game is not what you usually see on Steam. In Garry's Mod, you enter a physics sandbox which provides you with tools to make what you want happen and leaves you to it. You can play alone or join thousands of other players kidding around and playing with physics. If you do try this game, do check out its Steam Community Workshop

Garry's Mod or GMod (stylized as garry's mod) is a sandbox physics game using a modified Source engine, created by Garry Newman. Garry's Mod was originally a modification, a "mod", for Valve's Half-Life 2, but was later made into a standalone game. I ...   more on Wikipedia

Worms Armageddon is a strategy platformer game developed by Team 17 Software. The notorious war-urging earth-dwellers are back, and they want revenge! Prepare for a dose of hilarity, intensity, and cruel and remorseless action! To make the warfare as intense as possible, an arsenal of weapons and tools is available for every inconvenient situation you’ll find yourself in. Try out these props either in single-player deathmatch, various multiplayer modes, or in a campaign mode with over 40 missions!

Worms Armageddon is an artillery strategy game developed by Team17 and part of the Worms series. The player controls a team of up to eight worms in combat against opposing teams. ...   more on Wikipedia