Take a look at this!

Here's another game you should look at just for
the hell of it - Castle Crashers's For the 360 or Ps3!

So basically some "bad guys" have stolen your Princesses and your kingsends you to get them back , on the way to get the princesses you have to fight such creatures as Giant Bats , Aliens and other Knights! It has a 4 player Co-op which has a very nice art style , kind of remindsme of Chibi's or whatever , Everyone has a bigger head , and a smaller body , but it still looks very very cool!

The Fighting is done in a classic Beat em up side scrolling style. The enemies are innovative and very challenging at times so it's a good plan to have a buddy backing you up. You can level
up your character by beating the "bad guys".  The game is
extremely fun with 4 player co-op , get your friends
on your Xbox or Ps3 and start beating em up!

The music is absolutely Top Notch!
Take a Gander

It may seem annoying to you , but you'll get used to it!
There's a lot more where that came from , check you tube for the
main theme , that thing is just epic!

so what have we learned?

-4 player Co op is good
-Beat em ups are fun
- Music can change the game dramatically.

Castle Crashers is for sale on xbox live for 1200 Microsoft points last time i checked , and i don't own a ps3 so i don't know how much it costs back there

There's a demo for it too , so try that thing out.