got a couple of issues: 1) when you mouse over the upgrades bar, you have to wait until it is completely gone and then wait a moment to be able to throw the boxes again, and 2) the upgrade buttons don't highlight when you have enough money but have the upgrade menu open, you have to wait for it to go away then open it again
had a glitch where i had exactly enough exp for the next lvl
so it kept saying lvl up, then saving, then lvl down and saving again
it did this until the next enemy was killed, which was a while coz it was lagging