Skullgirls is a brilliant little game, you should go and buy it.
Oh, so you want a little more information. This 2D fighting game developed by Reverge Labs is a really good example of what the genre can be like with the right level of attention is paid to its design.
It reminds me of the old-school Street Fighter, before it started with all the ultra turbo whopper bullshit it started adding to its titles. Everything about this game just feels right, the music is a perfect fit, I love the art style, combo system just works and I adore the characters.
This game is out XBLA & US PSN (EU will be available soon I hope)