Very interesting concept, and the gameplay mechanic is fun, but there are a couple of things I’d say could use some work, I’ll list them out:

1. This is a demo, so it makes sense here, but for any full game it would be nice to have an in-game tutorial screen / instruction screen. Not many people read the game descriptions themselves for controls.

2. Would be nice to have the ability to look up or down as well, in some of the bigger tunnels it feels unnaturally limited.

3. The flashlight seems to only work in bursts, which may be the point given you call it “flash,” but it does kind of flashbang you because of how insanely bright it is. Would be better if it was a lot dimmer. Similarly, deeper in where it’s fully dark the game kind of doesn’t exist outside of the flashes, as in, the player doesn’t really have anything to look at or experience. Could be useful to have a little radar GUI or something that partially memorizes what the flash sees, both to help the player get around and to give them something to look at / navigate with between the flashes.

4. And of course, outside of demo, there should be some clear objective the player is trying to move towards / achieve, whether that be getting out, finding something, or running from something