Hi, so I liked the clean interface on your game and it was really easy to get started, but there wasn't enough visual feedback on the main screen after purchasing things, the only way you know things are changing is that the $ keeps going up.
Additionally, I went through all of the first round upgrades in less than a minute and didn't know if any more upgrades were coming or not (they did) but I didn't have any compelling reason to keep playing because there just wasn't enough visual feedback on the screen. I'm not sure if that changes, but if so, it should happen sooner because your players will give up if they don't get it.