Cars 2

Track design is more ambitious, graduating from simple broad curves to tricky chicanes and hairpins. There are short cuts and Easter eggs aplenty, and each location is explored and reconfigured to suit six tiers of themed missions.

Straightforward races are joined by battle races, combat arenas and more specialised survival modes where you must keep the timer going by destroying enemies or collecting shield batteries. There are also a couple of multiplayer modes, though these are offline only and support just four players.

There's a half-hearted attempt to weave some story into the action, but it doesn't really work and the rather clunky and long-winded menu system makes it tricky to keep track of progress without flicking up and down, backwards and forwards, through lots of icons.

Cars 2 is chunky, pleasing stuff, and with dozens of characters all drawn in the familiar wide-eyed Pixar style, there's a lot for children to enjoy. Where the game comes unstuck is in its wonky difficulty curve. There's a crude spike around Tier 5, where the skill requirements shoot upwards. It's hard to put a finger on precisely what changes, but there's some tweak in the countdowns, the agility of the enemies and the tenacity of rival racers that makes the game hit a brick wall.

The inability to easily switch characters between stages compounds this problem, as a slower, stronger car might be ideal for a combat stage but virtually useless in a challenge where speed is of the essence. Having to quit out, return to the core menu, then restart as the racer you want is a lumpy way of progressing and many kids probably won't understand why their favourite car isn't up to the job.

It's not just that the game becomes harder - that's what you'd expect and hope for - rather that it suddenly becomes almost impossible to win, particularly for the game's intended audience, as Cars skews much younger than other Pixar brands, appealing mainly to the five- and six-year-old age bracket. Failure feels unfair, heightened by the steady introduction of ruthless environmental hazards, and making young players feel cheated is a good way to turn them off. That's a real shame, since developer Avalanche Software did such a fantastic job of understanding the ways children play with last year's delightful Toy Story 3 sandbox.

As it is, Cars 2 is a simple yet robustly entertaining kid-friendly racer that switches from accessible fun to gruelling grind in the blink of an eye right before the end. This may not trouble many of its players, who will be happy to pootle around in the game's earlier stages, but it's just enough to tarnish the game as a whole and hold it back from must-have territory.