Transport the aquanauts with your submarines to the right caves.
Avoid being hit by depth bombs or sea mines.
Collect points by destroying enemy ships with your torpedoes.
99% of the game graphics & sprites have been created with Blender. To efficiently pack those graphics and to improve load times they have been put into sprite sheets.
I used the PhysicsEditor (PES) not for "normal" collision detection but in slightly different way. I used it as a tool to draw the shapes around sprites, wrote my own exporter and used the resulting polygons in my program. These polygons have been created for the coast/land and as well for the subs. I then used my own algorithm for collision detection.