I had fun, the concept is very cool. I had a lot of difficulty finding the other submarines, the mechanics were pretty clear but I just never could quite locate more than 1 or 2. I'm used to bullet hell games with a much faster pace, it took me a second to adjust to a more cautious and thoughtful play style but overall I kinda liked it, it took the concept of bullet hell and built on it instead of just being a carbon copy of the classic arcade games. If I were to come up with a design note my only thought would be maybe having an easy mode with a faster sonar rotation. I think it is playable as is but it would give new players to the game a chance to get their legs under them before jumping into the regular challenge, and I see it has been called out already but just some level boundaries. Overall really solid, great work for the limited amount of time!