If you want to buy a game that will test your rig (aka bring it to it's knees) you also could buy a cheaper PC, that will bring it on it's knees by some games, AND you save money

Or try Minesweeper! It's tactical!
Serious now

Might give Anno 1404 Venice (don't like the succesor Anno 2070...) a try (it's sand-box style, but it's a nice game)
Try Company of Heroes (tactical) --> the 2nd comes out 2013
Not heavy games, but might just have fun...
If you like Metro atmosphere, try S.T.A.L.K.E.R. (I think it's quit te same atmosphere)
I have them both, but never played them a lot (as all of my 564168463168463515864 other games...

)
(I bought STALKER because it says: "Supported by ASUS" on the flash screen when the game starts hehe) --> Yes I am ASUSfreak

EDIT: well it might be because it was installed on a ASUS laptop
Edited by ASUSfreak - 10/1/12 at 7:45am