ok here is a list of games you have, no, need to play:
system shock 1&2
dwarf fortress(you will need a guide I assure you, also search the lazy newb pack you will thank me later)
fallout 1&2 (ignore the graphics)
Black & white (the last great god game)
Spec ops the line(apocalypse now simulator)
this war of mine (cry and be depressed)
Civilitation any iteration (harder than chess and more engaging)
Age of empire 2 hd (one of the best RTS and the almost unbeatable champion of the genre)
Terraria (not a minecraft clone I assure you)
Crysis 1(ignore the second one)
sorry if most of these are long games, but they are great games I assure you, even DF if you can ever understand it XD
edit:
forgot Chrono trigger(better than all final fantasies out there I tell you right now) XD