If you have played 'Derelict' from Atomic Edition you know quite well what to expect. But instead of a ship there's now a submarine. At least half of the level happens underwater which works quite well. Don't spend too much time there or you'll run out of oxygen. Luckily there are enough scuba gears around the level. Design is good and shadows looks nice. Overall atmosphere is dark because the submarine seems to be out of lights. You'll encounter lots of Octabrains underwater. There are some cool effects like somekind of a meltdown sequence and some missile launches in the end. The worst thing in this level are puzzles which are really hard. I had to use 'DNSHOWMAP' and 'DNCLIP' all the time to proceed. It really spoils the gameplay feell when you have to use cheats. Worth to download and very good if you like very hard puzzle challenges (I don't). Average player might enjoy this level as long as he doesn't have to use cheats.