Garry's mod is a fun game with multiple gamemodes and minigames. If you don't like any of them, you can just make your own. We highly recommend TTT.

Tomb Raider is a beautiful open world story game that fallows Lara Croft through her archeologist related adventures. Hunting, climbing, shooting, etc.

The Stanley Parable is a fun and hilarious game where all of your decisions have a different outcome. There are so many endings to enjoy. #BroomCloset

Left 4 Dead 2 is an awesome level based zombie survival game that is heavily improved by the mods in the modding community. Thank you Valve!

47 Chromosomes™ recommecnds "Counter-Strike: Global Offensive" for its competitive playstyle and fun community and casual gamemodes. Two thumbs up!