This game is very very addicting. There is nothing else like it. How many Navy/water games have you seen? This is one of my all-time FAVORITES now. My only complaint is that you can not see through the periscope. It is strictly an attack sub profile...shooting at other underwater targets. The few surface targets can only be attacked on the surface with rockets, NOT torpedos.
As long as you realize this is an attack sub scenario and that 90% of your targets are other submerged targets, you'll have a BLAST!! Also this has arcade type graphics. Don't be expecting true realism.