The game seems very good and interesting, but who the hell thought that it was a good idea to make a game where you need to be pressing keys like F1 or F2 in order to progress, and also press ENTER to open a door? It just feels extremely uncomfortable.
What's wrong with using the normal keys like "E" or the Left Mouse Button?
And then I got stuck because I couldn't enter a 4 digit code. Why?  Because the game asks you to use exclusively the NUMPAD, which I don't have in my current wireless keyboard.
Again, the game is good, but it's currently ruined by the weird controls.

Games like this should at least give you the option to configure the controls layout, because it's literally unplayable to me in its current form.

Sorry for the issues.  

I use ENTER to add a little sense of tension with having to take your hand off the mouse temporarily. Since I make shooters, I like using it because it amkes the player temporarily defenseless.  

F1 and F2 were just oversights.  I assigned them and left them as is to work on other stuff in the game.

The keypad should've worked without the NUMPAD. I am not sure why it wasn't working for you.