Cult shooter Every Extend Extra may not have reached the same acclaim as Q Entertainment's other PSP game, Lumines, but it's a pretty solid addition to one's PSP collection. In Every Extend Extra, players must strategically blow themselves up and create chains to damage enemies. The unique visuals and hypnotic soundtrack create a surreal experience. But be warned! The game is relentlessly difficult (unlike the XBLA sequel).
You can get it for $13 shipped at Play-Asia. It's a rather interesting PSP exclusive, so you may want to give it a try.