At the bottom is the jam: a car park crammed with cars, vans and buses, each painted a colour and pointing somewhere. Tap one and it drives out along its arrow - if anything is parked in the way, it only bumps and honks.

Above it a queue of passengers winds through the park in colour blocks, and every vehicle you free pulls into a bay and takes the passengers of its own colour with it. That is the whole squeeze: a bay only leaves when it is full, you only have a few of them, and pulling out the wrong vehicle fills one with passengers nobody needs.

Clear the queue before the bays jam up and the level is yours. Levels are generated, so they never run out, and the lot is laid out in ten different packings - rows, rings, herringbone, spiral, sunburst - across thirteen worlds that change every five levels, from City Park to Snow Town.

Coins buy extra bays and three boosters: VIP pulls any vehicle straight out, Arrange re-sorts the queue, Jumble reshuffles it. There is a seven-day login reward, a weekly win event with four prizes, a daily chest, a VIP pass for double coins, and a profile full of lifetime awards to finish off.