The attack randomly working felt more frustrating than fun the way it was implemented. The way it just let you spam attacks until an attack worked just made it button-mashy, but in a bad way. I will admit bad luck is hard to make into a fun game mechanic, leading to pitfalls like the one you stumbled into here.
The final boss I think attacked me at the platform once? but otherwise stood there and took attacks from me.
I spotted the aspect ratio problems you mentioned on your page, as well as the white of your graphics not matching the white text of your HUD and the out-of-scene black being deeper than the darkest tone of the spritework, making for 6 colors on-screen at some points.
Regardless, it's more complete than what my team managed to submit, so that counts for something.