Great work on the graphics. Once you get some more foreground assets made, this will look great. A reef level will look beautiful. The controls are floaty but will be well suited to mobile if you want to go there.
Immediate concerns/bugs. I found workarounds for most of these but I would have dropped your game here if I wasn't reviewing it.
- On the pilar that juts out of the water on the way to the cave (near the surface with a teleport), I can get stuck out of the water on the pillar.
- Is that cave a dead end? I couldn't find a way out.
- Health as a white circles is way too subtle. That is probably placeholder though.
- Is there a way to recover health? Restarting when it's all gone sucks.
- When I CTRL+ESC from fullscreen then go back, I can't input into the game anymore. Windows 8.1.