Well, I downloaded and tried out the first level. A lot of problems, no bugs, but there is a lot to do. So I can give constructive criticism easy and in one go, I took screenshots of all the problems I had with that level. I have made a super image and attached it to the post, you may need to zoom to see some bits. Each image is labelled with a number, and in this post I'll talk about each image.
Image 1: The absolute first thing that hit me was the crazy arrangement of huds, and the big white square on the top right of my screen. What is going on? Why is my health at the dead centre of the screen? Why can't I fully see the mp-40 hud image? Why is there a big white square with a small picture of a person in it? All of these things don't make a lot of sense. I'd strongly recommend sorting them out, they're all over the place.
Image 2: Why is it there's a door that opens to the middle of nothing? I walked up to this door and it automatically opened. It makes no sense whatsoever. Perhaps the door should be made static, because I certainly hope this wasn't intentional.
Image 3: Exact same issue as before. Perhaps you should test your own levels more thoroughly, as you'd certainly come across this issue. Also test your levels thoroughly (if not more) after building the game, as its the result the player will see.
Image 4: What's wrong with this picture? A modern day soldier is swinging her knife at me, but in a WW2 prison. What?? Looking back at your description now I see nothing that states WW2, so you're let off there, but this does feel incredibly out of place.
Image 5: Not to big of an issue, but several things need fixing. A), The guard turned around and did nothing to me when I encountered him.
B), The text stayed around and I don't know why. If the guard was already dead, it shouldn't be advising me on how to kill him.
C), does killing him stealthily give any reward? There's nothing in the ahead area (I think), so why should I bother with stealth?
If you were just trying to give the player a bit of a tutorial or demonstration of controls then maybe add hint:, optional: or tutorial:, or something to the beginning to make this clear.
Just some things to clean up
Image 6: Seriously, what's this? Is there a reason the door is like that? I certainly can't think of anything.
Image 7: Small issue but worth noting, the lights aren't actually attached to the walls. Easy fix.
Image 8: Empty rooms are bad for a game, fill in area's with detail. Anything will do, like you did with previous rooms. It almost feels lazy that nothing was put there. Needs to be changed, its a sore spot for the game.
Image 9: Exact same deal as Image 8, except there is an entity in this one. Also, I might ask, why is there a table with war planning material tucked away in the corner of a room and absolutely nothing else? Have you considered filling in the room? It feels hard to justify not adding anything.
Other things that need consideration are:
-Get rid of those stock menu's, loading screens, sound effects. They give a bad impression on your game, it tells me that you haven't even gone to an effort to change them out. While I understand you may not have made custom menu's or anything yet, but anything even down to a one minute job in paint would do. If its W.I.P., then nothing fancy is needed, but it just needs to be something other than that stock menu setup.
-Why can't I pick up enemy weapons? It feels entirely illogical that I can't simply take the weapons from the people I kill. If it becomes to unbalanced, maybe try to ration out ammo throughout the level.
I could go on, but I won't for the moment. Like I said at the top, no bugs encountered, which is good, but some pretty bad flaws in the game. I know this is only alpha, and I know it doesn't represent the final product, which is why I'm recommending the changes
now, not later. Some of those changes are desperate, if I'm to be honest. Some fixes are little but will raise the standard of your game dramatically. I hope I haven't been to harsh with my criticism, but what I say is realistic.
Try to remember this when making your game:
Does it break the immersion?
Is that even plausible?
Is there a logical reason for this?
What kind of detail would this room have?
Do I have enough detail?
Little things that should definitely clean up your game.
Oh, and I almost forgot to mention. I liked the lightmapping, it was a good quality and the shadows were well cast.

- An Instinctive Fear IndieDB page, download demo today!