Theme That Plays Continuously During Both Traversal and Combat Screens: Kakeru Koma no Joku by Masara Nishida from the Burst Angel OST.
This is for when the action is relentless, a theme for a running battle, if you will, through some convoluted military installation or mad science facility. Flashing red lights and blaring klaxons may also be appropriate.
It's short, so I recommend looping it for fifteen to thirty minutes or so.
For additional excitement, play it loud from your mobile device while moving through the passages of some complicated space. At regular intervals, imagine enemies jumping out from behind barriers, or phasing ectoplasmically through walls, crashing down through ceiling panels, or lying in ambush around blind corners. Arm yourself with one of those little plastic cheese cube piercing swords, and slash away at phantom enemies to your heart's content.
