I really liked the environment and the concept of the game. I also admire how you've implemented the visual side of things (excluding the post processing effects).
To start off, the main menu was great, the idea and the design were good except for the post processing which I will be talking about it later in this comment.
There were couple things that you could've done better. The first and the most important is the game play. I understand that this is just a "demo" and you didn't have enough time to fully create the game, however I at least expect to play the game. All I had to do is press "D" key (to move forward) the whole time which made me feel bored after some time to say the least. Maybe next time you can make player interact and discover for himself the story rather than just printing dialogs out on the screen? :')
Second, when the dialog starts printing on the screen, the sound it makes (the "beep" sound) it's a bit too loud and later for me, it was annoying.
Lastly, the visuals. I'm not saying the models and the visual concept was bad. I'm talking specifically to the post processing. Some part was really hard to see (especially on some monitors, i've tested on both TN and IPS panels both configured properly), and the amount of grain you've applied to the game was a bit too exaggerated that after some time, started hurting my eyes. What I would suggest in this case is lower the vignette or perhaps add some post exposure and lower/disable grain.
Anyway overall, the concept of the game was good but the implementation was just not enough. I would like to see the full game when it gets released though.
Edit: Fixed grammar