This is a great little alpha! I love the mix of influences and the visual style you're going for is wonderful, you've really nailed it. It's still *very* clearly an alpha though - AI is pitiful and missing some barks/shouts to let you know what state it's in /what's going on, if they're alerted etc, and the sound design clearly doesn't lend itself well to an regular first person shooter as opposed to a stealth shooter (also IMO - the pistol should be able to instantly headshot guards as long as you're not too far away. Often it'd take two, or even three shots in the head to take down a guard.)
The opening levels design feels quite sprawling, and rewards you for exploration and hunting for items (like finding the night vision goggles and that tunnel!) - which is great.
All in all, I'm definitely gonna be keeping an eye on this project, it looks very promising! :)