Never underestimate the raw power of unbridled charm. LocoRoco is a platformer with a unique control scheme and a one-track mind that has you essentially performing the same handful of activities at roughly the same difficulty level from start to finish. So in long play sessions, you might find yourself a bit put off by the gameplay's relative monotony. But that winning charm, combined with a dedication to playing in short bursts, makes LocoRoco a fun little diversion.
In the intro, you're shown a peaceful planet, where the little globules known as LocoRoco live. The planet is attacked by the decidedly evil forces of the Moja. Your goal is to somehow restore world peace by occasionally bashing the Moja and generally rolling around. The game is broken up into five worlds and each world is broken up into eight levels. While each world does look a bit different, each one also has the same types of levels in them. So, for example, you'll see a fast-moving ice level each time around.
The gameplay in LocoRoco doesn't really put you in direct control of the LocoRoco. Instead, you use the left and right triggers on the PSP to tilt the playfield, causing the LocoRoco to roll around. If you hit both triggers, you can cause the LocoRoco to jump. There are several collectable items in each level, but the most important thing to get are the large berries, which make your LocoRoco grow. There are 20 berries in each level. Most levels also have tight spots in them that are too big for your ever-growing LocoRoco to fit through. In these spots, you can tap the circle button and cause the LocoRoco to split into multiple pieces, making each one small enough to fit through whatever gap is on your way. After traversing the small territory, you can hold the circle button to get your little blobs to form back up into one big clump. Along the way, you'll also encounter different-colored LocoRoco, and you can select which color to use before each level.
Your goal in each level is to merely get to the end. You'll encounter some resistance along the way, but not very much, and bopping the Moja by jumping into them isn't too tough. Instead, your real goal is to explore the level and find hidden areas by attempting to either bash through walls or just float through walls that aren't actually there. In these areas, you'll find more berries, collect more pickories, which is the game's currency, or find little guys known as Mui Mui. These guys will often leave behind a new, unlockable part for the Loco House, which is one of the game's side options.