Very nicely made.
The concept, graphics and atmosphere of this game were really great. The whole idea of giving the war game a new twist by having 'tanks' that evolve and upgrade by picking up the remnants of vanquished enemies is good, and the watery environment and sounds were pretty cool.
My main problem with the game was that it wasn't remotelyy challenging. Normally I'm more likely to complain that a game is too hard, but in this one even the biggest enemies I found were basically cannon fodder. The enemies' weapons fired one shot at a time whereas I could fire volleys that practically filled the screen.
I played it until I was failry sure my tank and weapon were as big and advanced as they were going to get, then closed the game window.
My advice would be to keep the basic elements of this game, but work a bit on structure and increasing difficulty to keep it interesting. It's a really nice game.