Today sees the release of the rather expensive XBLA game "Penny Arcade: Episode 1." for a huge total of 1600 of your MS Points you can purchase this RPG now.
You start the game by creating a character and then playing the story mode which looks like a comic book with all the speech bubbles and screen transfers.
The only thing i am really impressed with is the Graphics, and they are really good and matches the spiderman game on the PS2
Apart from that i would not bother, save your 1600 points towards some Rock Band songs!