Welp, with the update, it's much better! Playable.
However, not so fond of the gameplay, for several reasons.
Feels awkward at times. You don't know if shooting has any effect (feedback effects would be nice, like sounds when you hit correctly, visual cues). for example, when shooting the pipes, wasn't so sure where to aim at. The hitboxes seem too vague. It's a very difficult to tell when you're bathing in radioactive stuff or not and sometimes you're not even sure you were supposed to be hit. While "feeding the crabs" I assume your goal was to take the red box (i assumed it was fuel though?) and then I have no idea because green boats keep taking it. You can take them down, but at some point they don't get down anymore, meaning it's literally impossible to take the red box with you :/ Another thing is that it's very hard to tell where you are going and very difficult to anticipate your trajectory. (it often happens in the jam, it's not easy ealing with a 64x64 resolution)
Also, but that would be a bit more personal, not so fond of the way the graphics are. it feels like "compressed" higher res graphics at some points. (you said you were using a method of layering and 3D and stuff; well that shows there) - not the case for the boat though
The audio, although nice, doesn't feel like it fits the game to me. wouldn't associate easily metal with boats, especially when you can't just be reckless and go fast (as you need to carefully avoid every obstacles and aim at stuff)