Flow is one of those fun games that appeals due to its initial simplicity, then hooks you in before you know it. The Windows 8 game was originally written for Windows Phone and is thus fairly stripped back and lacks frippery. In the best tradition of such games, the simplicity belies how tricky it can be complete levels, making it difficult to resist another quick game or six.
The aim is to join up blobs of the same colour on a grid of between 5 x 5 and 9 x 9 squares. This is easy enough – drag a line between one coloured blob and the corresponding one to link them up. The tricky part of the game is that you must fill the board with these flowlines or pipes and that these can't overlap.
Thankfully, if you run into, say, a blue pipe when attempting to hook up the yellow blobs, all that happens is you break the existing connection and have to find a new route to connect them. There's only one right way of successfully connecting matching colours, so it's best to work out the potential bottlenecks and how to avoid them before you start creating the flow lines on your grid.
You can play against the clock in a time trial or attempt to solve the grid in the shortest possible time. This can be anywhere between 30 seconds and three minutes, depending on the complexity of the grid and the level you're on. Free play is an easier starting point than playing yourself against the clock. (See also: Windows 8: the complete guide.)
Be warned: there are 300 levels to the free play game, with a random generator for the time trials adding even more. By level 10 we found ourselves silently berating ourselves for taking more moves than necessary to complete a level – a sure sign that this game had got under our skin. For more on the changes in Windows 8 and how to use them visit Windows 8 Advisor. For detailed advice on installing Windows 8 Release Preview, read our article: How to install Windows 8.