Deeper than you think and you can fire off a turn very quickly when you have a spare moment. You can have up to 40 matches on the go at once too.

Really easy to get into and super fun. Becomes properly challenging as you try and get a perfect score on the later levels. Easily worth the price, you'll get a lot of fun from this little gem. Good music too!

If you enjoy CCGs and doing arithmetic, then you'll enjoy this. Pocket Tactics have a good review of the game which spurred me to check it out and I wasn't disappointed. Engrossing and much of the opponent dialogue had me chuckling.