Nintendo's free-to-play puzzle title Pokémon Shuffle has now been downloaded over 3.5 million times.

To mark this occasion, Nintendo has opened a special Celebi challenge, which runs from today until May 18th. Successfully completing the challenge earns you 1000 coins, and as you might expect, you'll need to be running the latest version of the game - 1.1.11 - to take part.

3.5 million downloads is certainly nothing to be sniffed at, and would suggest that Nintendo's free-to-play experiment is something of a success. Are you one of the many who have taken a chance on this title? Let us know your feelings by posting a comment.

[via serebii.net]