Excellent work! I really enjoyed it. Aesthetically, the game is well-crafted, and the mechanics are very entertaining.
I liked the variety of weapons, although I think it needs a bit of balancing; the HK pistol seems a bit too powerful compared to the others.
I had a bit of trouble using the torpedo launcher; the fact that it consumes all AP makes it challenging to avoid exposing the unit. Perhaps you could consider giving it an area of effect attack with slightly reduced damage that costs 1 AP less or has fewer rounds.
I also really enjoyed you added underwater mines; it was fun to see the AI getting caught by them.
The interface is also very good, very intuitive. I would like to be able to rotate the camera with Q and E as in most games, but that's a minor detail.
Overall, the game seemed great to me. I hope you continue working on it!