The game gets fun when you beat it. But the road there is mid at best. Every upgrade kinda makes you beat the next level, which makes the level harder, thus nerfing any upgrade, so at any point you feel like you're playing the same level over and over until you prestige and then it's too good. Having the option to choose your level would improve this greatly, since sometimes you just want to earn cash, and pegs getting tougher means they aren't destroyed and you don't earn as much money as if you just cleared an earlier level.