Absolutely beautiful, amazing use of sounds+graphics! Only complaint is that level 12 feels almost random and started to get a tiny bit frustrating. Otherwise 5/5.
Great fun! Auto-save and slow pace make for many hours of fun.
Feedback: The intro was so detailed... How about some more (skippable) exposition between levels? I forgot why I'm even playing.
Bug: Sometimes you can't shoot at all. Refresh the web page and it works again. Several others have confirmed this bug.