Wonderful game, cool pixel art and nice attention to detail in all the props you've placed around. When the little things are animated (e.g. the water dispenser) it really adds to the overall effect of the game. Talking about the effect, it seems you have achieved it relatively well.
This can totally be a complete and full fledged game once you add more content. I really liked the element of exploring the game as two different characters, maybe you could in fact add in a split-screen multiplayer mode where both characters can be played out simultaneously and the gameplay alternates between calm exploration/puzzle solving and combat for both players. I'd also love an extended version of this where the psychological elements in the story are explored further.
I understand that this is just a demo so I'll definitely be looking forward to a full version. Great potential, keep it up!