This game can be fun at first, but like a lot of free games, you'll need to be prepared to spend a fair amount of cash to keep playing. At first, it's reasonable, but once you get to the higher levels (>Mine 45) the spend requirements increase dramatically. I'm at Mine 49, and to keep it playable will cost me between $50 and $100 US, and that amount will likely double every week from now on. If that doesn't faze you play ahead, but I'm done!