Stuck at level 14?
The checkpoint for a new scene is every 15 levels and if you forget to buy scene upgrades while you're going along the game will get "stuck" like this until you do buy the required upgrades. The optional upgrades on the left don't need to be bought but they look nice since those move around.
Buy the scene upgrades at the bottom until you either can't buy any more of them because you're out of resources or until it says "scene completed", then you will get the continue button back.
Last edited: 03/11/2015