Great FPS it's also F2P. Definitely worth your time

Best RTS series I have ever played, Please for the love of god try it.

One of the first RPGs I fell in love with, Its Open world with afew sidequests, and the option to become any class you fockin want, Ghost swords anyone?

Pretty amazing old game where you can make an army, take over the land, and become king, or remain a vassal and help your lord to become ruler

X3 Is a fairly slow paced empire building strategy-ish game that requires alot of patience, but if you have some go ahead and look it up.

Garry's Mod is an insanely fun sandbox, roleplaying, FPS, etc. Game that is great to play with friends, My personal favorite gamemode is DarkRP.