Very nice game! I was a bit confused by the file size, though I think it could be a lot smaller.
You could re-encode all 9 BGM tracks to reduce their size. I also found the debug console on ´ /F12, which is really nice, but replacing it with a simple debug menu with buttons could potentially reduce the size there as well.
Also, converting the PNGs to WebP could significantly reduce the file size without any noticeable loss in quality.
With all of these optimizations, I think the overall game size could potentially be brought down to around 22–30 MB.