Interesting concept, the game looks nice, I didn't have any trouble understanding the controls.
For a really long time I couldn't find any other keys, I feel like I survived pretty long time, killed a lot of the rats and explored big part of the map and for a while I didn't understand where to find the other keys, eventually I found one but I feel that it is too difficult to find them.
Adding an explanation of the conditions to beat the game cloud help.
Also after death you still retain control over your character to some extend and there is no way to restart the game without truing it off.