Batman Arkham Asylum
There has been a cautious return to the Metroidvania genre lately in the sense that mainstream games borrow more and more elements from it. I definitely approve of this, and while Arkham Asylum could have taken it further it was indeed a very nice way to spend a day.
In addition to the feature-based progression that is the staple of Metroidvanias, the game sports a rather advanced hand-to-hand combat system. When fighting armed opponents by sneaking in from the shadows, taking out an enemy and then sneaking back the game is a true joy to play and perfectly captures the essence of the last two movies. When fighting unarmed enemies it is usually good entertainment but occasionally becomes tedious as enemies are lining up to strike you in the back as you attack someone else.
My main gripe with Arkham Asylum is how disconnected the gameplay elements feel from each other, while the moves you learn during the game can sometimes be used in combat they are normally quite worthless as such and resemble a lock-key mechanic that gives you access to new areas more than character development. The same goes for the exploration and finding new things, while you do get a little experience from it (and a few things that do not matter gameplay-wise) there is little immediate benefit from doing it other than the joy of seeing the game. Nothing particularly wrong with that, I just personally think a more holistic experience could have been better.
But it is indeed a nice title, and I hope it helps set some trends in exploration-based action games.