If you're interested in playing Castle Crashers on your PSP, consider purchasing the game from the PlayStation Store (if it's still available) or buying a physical copy of the game.
The PSP version of Castle Crashers was released in 2010. It's a port of the original game, featuring the same gameplay, characters, and levels. The game follows a group of knights as they battle their way through hordes of enemies to rescue princesses from various castles.
Castle Crashers is a side-scrolling beat-em-up video game developed by The Behemoth. The game was initially released for Xbox 360 in 2009 and later ported to other platforms, including the PlayStation Portable (PSP).