Incredibly well made!
If you ever decide to expand on this game, please don't show the intruder if possible.
This game is genuinely really scary... Until I actually see what the intruder looks like. It's not at all that their design isn't scary. Just comparatively, not quite knowing what they look like is terrifying.
Think how the movie 'Alien' works by not sowing you the Alien's design until the very end, when the hero has fought their fear and is no longer afraid.