What's your favorite?
Mine would have to be Advance Wars: Days of Ruin. The story is cliche and there are numerous overpowered CO's and units but it's still an utter blast to play.
Examples of Post Apocalyptic Games this gen.
Fallout 3
Fragile
Gears of War
Gears of War 2
Resistance: Fall of Man
Resistance 2
Left 4 Dead
Left 4 Dead 2
Go nuts.
Pixel Art can be fun.