I'm removing 2 stars, 1 for each problem I had with the game.
Too hard, you literally start with absolutely nothing other than a puny punch that's too short to keep my char safe from enemies and deals about no damage. Just to kill those pot mimics I have to punch them like 5 times with an unreliable and short fist.
Another problem that isn't specifically by design is the input lag. There's none in windowed mode which's cool I guess, but it's very obvious and annoying in fullscreen, making the game borderline unplayable. Also I can't play in windowed mode because of the browser and my screen size.
The game gets cut due to my screen size and both the mouse wheel and arrow keys scroll down the damn page. The browser issue could prolly be solved easily by switching browser, but what do I do with my screen?
I think I'll stick to TBOI.
I'm still giving it 3 stars for the effort and I'll consider trying out the desktop version when I can. The graphics and music are good.