Really fun little game - echoing what others aid, having some way to track how many ships you ended up sinking. I could see this being a really cool sort of combat game about sailing through hostile waters, having to shift between navigating and attacking. The sound design was good, but could really be elevated by having more ambience to really give that "stuck in a polished metal tube" vibe the visual aesthetics are really going for.
Even just having the radar pings get quicker when a ship closes in, something to really drive up the tension, could make this knock it out of the park.
I really liked this one - it fills a submarine combat niche really well.