Very long soundtrack
The composers have created good atmosphere in this one. When you're searching for enemies, you hear ambient music, perfectly fit with level. Some tunes are just for underscore atmosphere (Especially MILITARY BASE MUSIC - There's a lot of drums), but some are really creepy (ASYLUM AMBIENT MUSIC, FACTORY AMBIENT MUSIC - One of most psychedelic tunes I've ever heard!). Combat music are heavy metal mixed with techno - Some ideas are really good (My favorites are FOREST FIGHT and ORIENTAL CASTLE FIGHT)! If you have PAINKILLER, you can listen those tunes from MUSIC folder.