Stealth stuff.
First off, this is really good. You seem to have a knack for writing video game music. It makes me feel suspense and thrill but it seems like it's building up to something and never really gets to it. I believe what makes it feel this way is that the drums/percussion keep picking up. I would suggest adding maybe another theme that it evolves into. But honestly, this is pretty darn good just the way it is. Just thought I would throw in my 2 cents for whatever it's worth.
Keep making music.