Hey there :)
I liked the game, it feels like a today's boomer shooter (which I love). I can highlight several things that could be fixed to improve the player's experience:
1. I can't turn the fullscreen for the game. It initially launched in a small window, and I had to do some technical things to expand it to a bigger one.
2. There is no sound of footsteps; it would make the game much more immersive.
3. It's way too dark in the levels; sometimes I couldn't see anything and had to find my way at random.
4. I initially didn't get my goal and the function of the SHIFT feature. Though I managed to figure it out, I would add a small tutorial window in the beginning that would explain the basics.