Games you'll definitely re-play ?

There are some games that are too good to be played only once or twice, games that should be re-played over and over just to be reminded of how awesome they are.

I will definitely play these again:

-Portal 1&2

-Darksiders 1&2

-Metro Franchise

-Call Of Duty: Modern Warfare

-Call Of Duty: Black Ops

-Mass Effect Franchise

-Bulletstorm

-Crysis Franchise

-Dishonored

-Prey

-Fallout 3

-Assassin's Creed II and Brotherhood

I may have forgotten some titles, though.

What are the games you'll sure play again ?