Castle Crashers is a side scrolling RPG developed by team The Behemoth (Alien Hominid HD also for Xbox Live Arcade). The title is arguably the best multi-player Xbox Live Arcade game but it is also hampered with many glitches and bugs.
You start out picking 1 of 4 different coloured knights. Each knight has their own special magic ability. Blue is ice, red is lightning, orange is fire and green is poison.
You advance through each level hacking and slashing your way through wave after wave of enemies with the occasional boss fights. There is a basic story of you trying to rescue 4 princesses that were captured by the enemies along with a stolen jewel but it isn't anything to write home about.