The basic concept is somewhat similar to Lemmings – get a requisite number of your charges to the exit by using their particular skills. That's, however, where the similarities end. World of Goo is essentially a structural engineering puzzle game (I know, I know, your eyes aren't exactly lighting up with glee at that description, so bear with me). You must use your animate balls of goo to create towers, bridges and other structures to get to the pipe representing the exit. Sounds simple, and as you start grabbing individual balls of goo and placing them near other balls to tether them together, it certainly seems to be. This is a game that's utterly intuitive to get into, but once you're a couple of levels in you'll also discover that it's a uniquely challenging physics-based puzzler.

Gravity, it seems, is a cruel mistress. Your goo balls create structures that sway and bend and can easily topple if unbalanced. This can be used to your advantage in some levels. One of the first in the game, for instance, charges you with bridging a small gap between two cliff faces. While you can build horizontally across the chasm, provided you create support for the structure against the cliff wall you're building out from, you can also build straight up, then weight the construction to the right, causing it to fall down across the gap. Like I said, the system is intuitive and straightforward, and the dynamic nature of the building process really adds to the charm. Fail and it's a simple matter to restart and try a slightly different approach.

World of Goo, then, is a pretty unique physics-based puzzler. It's also utterly charming, both in the unique visual style of the environments, the humour in the writing, the way the remaining balls of goo swarm about your structure and in the music, which ranges from 'demented fairground' to what can only be described as 'sleuths-r-us'. The only question that remains is whether 2D Boy can keep twisting and tweaking the level design to keep the game feeling fresh throughout. Based on the first chapter, we're hopeful that the guys can.