Dark Souls- yes it is available through steam and what not but the port for PC was relatively poor. Plus the online community is somewhat more alive on the consoles then PC.

Motorstorm Pacific Rift- If you are looking for an arcade racer of some kind I recommend this. Granted online has had it's plugged pulled a few years ago but the racing is still fun even on your own.

Lair- If you can get past the six axis controls they decided to use with it the game's story isn't all that bad and can be fun.

Kingdom Hearts 1.5 and 2.5- If you never played Kingdom Hearts well now is as good as ever especially when both collections come with three games a piece (granted one of those three for each are just cutscenes), for a good price.