French developer Mobigame is demonstrating that good mobile games aren't just about short term success.
It's just announced that its 2009 release Cross Fingers - a Pocket Gamer Bronze Award winner - has been downloaded 10 million times on iOS.
So, to celebrate, the game is free for the rest of June.Sliding trick
If you haven't played Cross Fingers already, it's a beautifully designed puzzle game based on the ancient Chinese Tangram puzzle, in which you have to slide angular shapes around a board into a finish position.
And even if you have completed the 480 levels currently available, the next update - due this week - will add another 120.
You can see how it plays in the following video.