You want superB games?
Okay... No order...
1. Age of empires 2
Old but still one of the best old school RTS
2. Rise of Nation
Not that old but one of the best newer RTS games.
3.Populous: The beginning
Simply because you're a god!
4.Dungeon Keeper II
What's more fun than having your own dungeon and minions?
5.Furcadia
Cool highly (and easy) customizable socializing/roleplaying game. A must.
6.Wolfenstein: ET
Simply because it's old school and WW2 with objectives. And has a funny levelling system in it (Oh, I love levelling)
7.Assasin Creed Series
Simply because you can climb and fight in a medieval city!
8.Fable Series
What's more fun than becoming a hero and slay countless enemies?
9.Knights and Merchants
One of those games that where you think of: looks dull. But when you play it, you're addicted to it.
10.Dungeon Siege II
An old school RPG which gets you hooked by it's awesome combat system and story.
11.Gta Series
Just because it gives you freedom doing things you want to do.
12.Oblivion
Because it gives you freedom and is more deeper than most RPGs Dont forget it's in medieval fantasy times!
Can't think of any other games that deserve to be on the list.