The game fits the theme very well. I like its simple gameplay and its consistent visual style. 

There's actually impressive and cool elements in this, like for gameplay its the smooth progression and some out of the ordinary systems like equipping and stuff. And for art is the giant background with parallax, its just perfect. The vibe is spot on, it would be really nice with music. But for the font, I think it might be too w i d e, makes it a bit hard to read in fullscreen, haha. Really nice job!

Is this your first game? I'm using godot too! Good luck!

First 5 seconds of ur game and I felt like I found a diamond in the haystack. First of all forget the objective of the game just the movement and art made me smile. Your game is inspiring. It reminds me that simpler is better. I loved the sound, the movement of the submarine. Played through the end because genuinely enjoyed it. It reminds me of why I love games even though there wasn't a story or a reason why you were stuck. I think just the vibe and atmosphere was super comforting. Great great job with the mechanic