A real corker here - and, despite the fact that it came out over two years ago (I think), in many peoples opinion it's still the best puzzler to date. In fact the notorious Dr B still can't get enough of it. And, as is the case with most of these things, it's excrutiatingly simple to play.
Basically lots of different-shaped bits fall from the top of the screen, and the idea of the game is for you to rotate these shapes as they fall so they all fit together neatly when they land at the bottom. Y'see, if the pile of blocks manages to reach the top of the screen you lose the game. But if you manage to twizzle them so they fit together neatly to form a solid row across the screen, then that row will disappear (thus making room for the rest of the falling blocks). Get me? (As with many of these games, it's a difficult concept to describe, but easy to understand once you see somebody playing it.)
And if you're thinking that this all seems incredibly boring and tedious, well, you're totally wrong. It's skill. In fact, its completely and utterly addictive - almost too much so in fact. It'll have you tearing your hair out!
It might look like a mad jumble of multi-coloured shapes to you, but play it and it all makes perfect sense (I promise). Quite frankly, if you haven't played Tetris you haven't lived (or something).