Good news! We just sent out reviewable versions of the game to all relevant age rating offices. That's ESRB for the US, PEGI for Europe, USK for Germany and AGCB for Australia. They will check out our game, and then tell us how old you will have to be to enjoy our game. Hey, we think it's fun for everyone, but they might disagree.
We're estimating it will be rated at 10/12+, depending on the rating system. So now we'll have to wait for those to return back, while we polish up the game a little more. It's mostly our coder, hammering out the latest bugs and implementing the messages required by Nintendo.
So hang in there! We're nearly done!