I really like the look of it, Gameboy window and all.
My main issue is the audio and the respawning. I get you're going for an aesthetic, but the music/sfx is so loud and shrill I had to mute it after about 30 seconds.
And there's this weird issue where you restart and a sword fish spawns in the first room so you're stuck in an infinite death loop.
After a few goes I managed to navigate the narrow passages and get the harpoon gun. Having to pick it up after firing was an interesting choice. As far as I can tell that's the end. If so, it's good start.
EDIT: This was recorded after my feedback.