I don`t think the keys work propperly, I saw a door with a ladder on the other side. (Untrapped and all)
But of course the door wouldn`t open. Then I went around the corner, and foud a key. I went to the dor with the ladder aigan, but it still didn`t open. Does the key work in another way than I think it does, or is it a bug? At least I think you can just run into the door when you got a key, then it will open.
Also, if you could add it somewhere so that we can see how many keys we got, that would have been great.
Overall, I love the game, I was actually planning making a similar game myself sooner or later with a slightly diffrent mechanic. This scared me A LOT the first time, then it was like scary and all, but something`s missing.