Sid Meier and Firaxis team up once again, this time for a space strategy adventure Sid Meier’s Starships. Travel the space with a group of starships, protecting various planets from various forces of evil. Your goal is to reach peace amongst galaxies, to do so you will need to create a planetary federation, securing your home world. Follow the non-linear story with multiple ways to win, engage in skill-heavy tactical combat and bring peace to space!

Sid Meier's Starships is a turn-based strategy video game being developed by Firaxis Games and published by 2K Games. The title was released on March 12, 2015 for Microsoft Windows and iOS, and an OS X version to follow. The game is a stand-alone tit ...   more on Wikipedia

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