I've been having a lot of fun playing Just Cause 2, the open world mayhem game from Avalanche. It's a sandbox game (ie: Grand Theft Auto), with an emphasis on movement that makes it more like Crackdown or Spiderman 2. Except, the awesome part, it's set in a huge tropical island that looks more like Far Cry. OK, that's a lot of game comparisons. But it works.
The gimmick in Just Cause 2 is you have a magic parachute and grappling hook. You can pop your shoot open in free fall, then grapple to something and sling yourself towards it. Or from the ground grapple yourself up a building, climbing it. Or grapple the ground and while zooming forward pop your chute and go airborn, slingshot your way around throwing grenades at fuel tanks and then grapple up to the enemy helicopter to board and hijack. It's absolutely ludicrous, and fun. Lots of stuff to blow up, too, in fact your primary game objective is to increment the "Chaos" counter by blowing stuff up. Nothing's quite as satisfying as flying into a remote army base to assassinate a colonel with a sniper rifle, throwing a couple of grenades at the SAM site, the jumping in an army gunship to shoot up the place.
Technically the game is marvellous. The graphics are beautiful, really great tropical vegetation. Fun physics which let you do various stunt tricks. The big innovation is you can use your grapple to stick one object to another. Tie a guy to your car and drag him behind you. Tie a propane cannister to a motorcycle for a jet boost. Etc.
A couple of caveats. The game is hard; I made the mistake of starting on a high difficulty level and had to start over because it was too hard. And the controls feel awkward at first. Managing the grapple/chute combo takes a lot of dexterity on the controller and it can be frustrating, but also satisfying when you get the skill. Finally the game story itself is ridiculous, with a plot bordering on offensive. Just ignore that and fly around and blow things up, you'll have fun.