I like the mood / tone your game set from the start, and it was a good story. The music on the menu and at the end of game was rocking. Oh, and that initial phone ring in the story line, startled the heck out of me...it almost threw me off my chair ... haha. =) But it speaks the mood that you have set from the start.
Admittedly, I didn't use much of the crouch option except for stealing that key in the second scene. I really liked the maze and the lean function came in handy. A crystal count would be a nice to have on the UI, and possible a count down timer. But the SFX were great indicators (when using the watch.)
And it was a bit of fun exploring for diamonds over the map.
The ambient noises in the scenes, set me on edge a little, not sure if because there wasn't much variation, but it did add to the mood.
I'm unsure if it was intentional, but the footsteps felt like time was ticking away as you were walking...which was a great.
The artwork was very unique and I liked it. I could see this game evovling into quite a tale if pursued, make sure to continue with the artwork.
Overall a good game! Thank you.