No More Heroes
Take the edgy design of Killer7, then add free-roaming controls and a lightsaber, and you've got most of what I've played of No More Heroes. The combat is, thus far, not hard, but very fun. Motion-controlled finishing moves and the High/Low attack dynamic make the fights really interesting. But mostly, it's just ultra-fast-paced, stupefyingly violent, and awesome.
I take a little issue with the camera, because while its orientation has changed since Killer7 - it's a third-person over the shoulder style view - the level design has not. Running down narrow corridors gets a bit irritating when the camera gets twisted around to watch my back instead of my front. Just a bit, though.
A lot of care has been given to the game's style, including Travis's pad (there's a pet cat), the save system (use the toilet), how you charge the batteries of the beam saber (by jerking it off), and especially the special moves, which are too damn cool, even the ones that don't do a lot. The screen goes dark, Travis yells something intimidating, and all of a sudden you're seeing a totally different sort of carnage than you've ever seen before.
So far all I've done is kill the (previously) 10th-ranked assassin after wrecking up his mansion, so I still haven't touched the game's overworld or its badass bike.
Also: the soundtrack is incredible. There are perhaps too few games that really pump you up with the music, but No More Heroes is definitely one of them.
Progress: 10th ranked assassin