I tried this mechanic before. The main problem is that the light should bounce the walls, otherwise you are close to a wall and cannot orientate yourself. It should also follow the mouse, because moving to flash again disorientate you. 

I think the "corners" to pass or move to another area are way to tight, making it hard to keep moving.

Interacting to pick up the key is a bit awkward, I was expecting taking it while I pass on the top of it. Probably you wanted to the player to be aware that the key was there? maybe a "shiny" effect when you flash it would help too

You could use the idea to look for ghosts :)

Graphically I found it very outstanding. I really appreciated the flashing mechanic because it's not exploited by many games, and the color/light gets along really well with the low-res style. Even though I didn't figure out how to go past the second lock, I liked it.

man its really cool i just wish there was an easier way to move from one camera angle to another cause right now you gotta try hard to do it