I'd played Facebook games before, inevitably giving up after a couple of weeks of tedious repetitive activity. This is probably good for my peace of mind. Zuma Blitz doesn't keep track of how much time you've spent playing. Late at night, I sometimes find myself resenting their skill. I keep losing out on the top spots to two of my friends: a teenage prodigy and a Finn with cat-like reflexes. What hold could a few brightly coloured pixels without so much as a 3D rendering engine have on me? After four weeks' play, I've already reached the 21st level and earned two bronze medals in my local leaderboard. It started out as harmless idle curiosity. 'Just one more game before bed' can easily turn into twenty minutes when you're trying to beat your friend's 270,000 point high score.

A weekly leaderboard allows you to compete against others on your friends list, and sometimes the competition feels very real. A variety of bonuses add to your score and increase your time limit, while power-ups make it easier to gain extra points. You have one minute to rack up as many points as possible. You do this by firing coloured balls to create matched chains of three or more, which then disappear. It's a simple enough game: balls roll down a path towards a well and you have to eliminate them before they reach it. I've been playing Popcap's Zuma Blitz on Facebook for about a month now. And now I'm about to stand up and tell the world. The only people who know are my fellow users.

I don't tell anyone about it, because I know they'll look down on me.

Zuma blitz on iphone