Subroc is an over the shoulder 1st person shooter where the name of the game is destroy as many alien vechiles as possible before they destroy you.
The aliens come in all shapes, sizes and colours (like u.f.o's, submarines, jet planes, stealth bombers, missile boats, the big black super u.f.o at the end of each level and the odd pirate ship or two.
There are fifteen levels in total and each becoming more tricky than the last.