Really very solid game, good old arcade-vibe gameplay. Reminds me of that old swedish submarine sinking game from the Windows 3.1/95 era.
Anyway, this has very good 2D graphic, the sound/background noises and the whole atmosphere is phenomenal!
I found one problem with the campaign mode, where sometimes after finishing a level (right now I am at Level 4), it doesn't load the UI/menu for going to the next mission. Not, that is hangs, but there is only the ship/sea animation, the background noises and nothing more. You have to press the ESC to get the standard menu. When you get this menu, you can only restart the level or go back to main menu. Hmm...