Well that was quite a ride :)
The way you incorporated first-person 3D movement in the vents and the harrowing intro scene was great, and the FP fights were a ton of fun visually and mechanically, loved the shooting sounds and various animations.
The aspect of being a team, but also being wary of betrayal, added spice. I loved that your baddest teammate is also seemingly the crookedest. Hey cool a sweet new gun, I should equip that on...wait...should I? hah! Some of the lategame decisions were real dilemmas, nicely done.
On one hand the maps and enemies got a bit repetitive, on the other the sheer fun of the way you handled combat visually kept me engaged, and I was bummed when it ended. I'd definitely play an extended update if you make one, even just to see the impact my decision have as it progressed.
Cool story too, and I dug the few items, skills, and equipment I obtained. Getting new guns then seeing them in action (and getting to use their 'Tech' features) was especially satisfying.
Awesome job, your game stands out in many ways!