I've noticed that you have a Zip file that's the HTML build, for it to be playable in the webpage there is a checkbox that you need to enable where you upload it in the list of files, here's a reference of mine: https://gyazo.com/2a6a592fe1a11204d82cf79ce4854d03.
I've set its settings to manual resolution but that depends a bit on your build/player settings.
Fun game with nice art and the boss mechanics, and the upgrade system is a nice touch.
The only thing I'd suggest is to improve the text formatting making it more consistent within itself, and taking it through a spell checker for presentation purposes. In example, some phrases started with caps, but some others didn't for the hotkeys list, and you've also used a mix of &, and "or". The amount of text used looks fine, maybe spreading it along the screen.
Cheers, i hope this helps ;)