Simple and fun.
It could have more though. Maybe you should make a new version, firstly I'd add a button allowing the player to mute it. I'd also add more obstacles, maybe not just squares but enemies of different shapes that do different things, such as expand or explode and if you're nearby you lose. On this game, I felt the different features and two different games made it quite addictive but after a while it certainly gets repetetive. I think you should work on it, maybe have colourful backgrounds and similar upgrades if you're going to make another. Not bad.