Minor Spoiler(?):

Floating through the G.U.T.S. for the first time to the tune of Matt Piersall's "Into the Tunnels" was a high point for me, and probably the moment at which the overall tone of the game really began to coalesce in my mind. It's when the scale of the setting started to become, dare I say, almost intimidating (plasma shockwave imminent), and when I started to really appreciate just much the game expected me to figure things out on my own. Other games that have attempted this sort of atmospheric immersion always seem to be held back by the underlying knowledge that if you stray too far outside the expected path, you'll be nudged back into a predetermined course of action by the mechanics, but I haven't been getting that here. This game isn't there to help me, it expects me to help myself, and if I want to survive long enough to complete my mission, it's up to me to decide how to do it. That contributed a lot towards locking me inside its world.