#22 - Infamous (PS3)
As guessed by Milkyjoe. Infamous was an impulse purchase for me when Gamestation were 'going out of business' and it was incredibly marked down and I liked the box art. After playing it, I wondered how the hell I let this game pass me by. Faffing around in Empire City with Cole - a surprisingly nimble and agile character with a full array of superpowers - was an absolute blast. In a different way to how GTA was enjoyable by having so much to do, in Infamous I just felt like exploring all the time. Add in a surprisingly touching story with a killer twist (never saw it coming but once it happened I couldn't believe how much sense the whole game meant) and I was completely sold on the franchise and Sucker Punch's talent.
Clue for my #21 - Oft-ignored sequel in a classic gaming spin-off series that offered 'double' the fun.