LocoRoco 2

There are, believe it or not, 45 cut-scenes of adorable gibberish, elaborating a story with two threads: one involves the Mum of the first game's boss, who is using her kisses to transform Mui Muis into a mischievous red rival race, Bui Buis. In the other, the floating, dreadlocked Moja bad guys have learned a "scary piece of music" that leeches the "vigour" from living things by surrounding them with cloying black clouds called Bunyo.

These Bunyo can be dispelled by bumping into them, or later, scatted wholesale by a new action that seems to be a pulsating soundwave. Bunyo clearance is permanent and accumulated; once you tracked down and repelled all the Bunyos, you'll face a secret boss.

LocoRoco 2, as you'll have noticed by now, is positively drowning in secrets and collect-and-unlock systems. Collect notes to unlock quests to unlock house items to unlock mini-games to unlock stamps to new levels to unlock more stamps to unlock items, and on and on, in virtuous circle of reward-and-more-reward. The stamps are probably the second-coolest sweetie, giving you images of all the flora and fauna of the LocoRoco world to arrange in dioramas of your own design (or match with silhouettes to - you guessed it - unlock stuff).

Better still are the toys and furniture items for the Mui Mui House. A simple one-room dwelling at first, the house can be expanded and populated with ever more Mui Muis who will joyfully interact with the beds, kitchen ranges, showers, huge vats of orange juice, drumkits, libraries and more that you furnish it with. It's embarrassingly cute, as well as being an odd and probably unintended nostalgia trip for those old enough to remember Little Computer People.

Gather enough Mui Muis and their King will appear, but you'll also need to use a cannon to defend the House for Bui Bui air-raids, or they'll nick your furniture. It won't surprise you to learn that the Mui Muis will thank you for their digs with gifts - secret stages or mini-games, or a LocoRoco short film to screen in the house's movie theatre.

There are twice as many mini-games in LocoRoco 2 as in the original: they include Nyokki Nyonyokki, a sort of game of whack-a-mole with the smiling pink extrusions, and Bui Bui Bwooooon!, which, astonishingly, is a full-fledged side-scrolling shoot-'em-up in which a team of Mui Muis in a makeshift airplane take on the bullet-storms of the Bui Bui fleet.

Loco Rider is the multiplayer entry, supporting up to four players on an ad hoc local connection. Mui Muis ride bloated Locos into battle. Naturally the tilt controls would make no sense, so instead you're directing jumps with the analogue controller, charging them up the longer you hold the circle button down. The aim is to barge into other Locos, knock them into spikes so they split, and in a disturbing display of cartoon cannibalism, eat up their little component Locos to become the fattest blob in town.

There's also, as you'd expect, a heart-breakingly silly and enchanting array of new characters and creatures, all rendered in beautifully clean and vibrant blocks of flat colour, and the whole thing moves as smoothly as melting ice-cream. LocoRoco 2 easily fills its predecessor's boots as the prettiest game on PSP, and makes such a virtue of that stunning screen that you can't help but feel a rekindled love for Sony's slab.

Whether it can retain the original's purism and charm whilst adding a healthy dose of reliable, replayable longevity is the question - and one level of show-floor, clap-distracted play is certainly not enough to provide an answer. But with its absurd variety, generosity of spirit and calculated feedback-loop of unlockables, LocoRoco 2 seems equipped to do just that.