This game looks great, and it nice and simple, plus well implemented!
I'm not so sure about the unwinnable state you can get into. With no satisfying end point, there's a weird end to the game if you miss the Marlin. The game also encourages playing it safe, as there is no real downside to going slow. Do you thing you might explore adding in a mechanic to encourage the player to take risks?
I am blown away by how polished this game looks and feels! Incredible for 48 hours work!