It's an interesting concept, and I can see it going places, but it's too buggy right now to play.
While I feel that the player movement is too slow, all jumping feels fine. Player does seems large for this type of game.
Don't force me back to the start when I press ESC, and consider adding some form of save system early in development.
Could pick up the keycard twice, by going back through the first door.
Game crashed after I moved through a door too many times. I don't know the exact cause, but it might be due to moving through a door when bullets are being destroyed (some crash due to yield perhaps). I could reliably get the game to crash by moving in and out of the same door a couple times while shooting.
When the game crashed a third time, this time while going through the second door without trying to break anything, I gave up.
Edit:
Played it a little bit further after that, trying to record the crash happening, but didn't encounter it anymore. The game did crash when pressing ESC at the end though.