So first off, I really enjoyed this. I think it has a lot of potential.I do think a few things could be done to make it better.
Some of the upgrades become less valuable the further you get into the game. What I mean by this is once you have all of the characters at 100% corruption, all you need to do is push forward to unlock multiple possessions to get every scene. The value of having multiple characters producing experience outweighs the value of small increases that upgrades give. As it stands outside of completion, filling out the upgrade tree doesn't do much. This could just be an issue of this being a demo and not seeing the whole game as it was intended.
I would also love the characters to get a bit more development, they all have their own quirks and personalities that can be seen in their dialogue and desks, but adding a piece of dialogue when they have a scene, when they catch you in the act or when having a joint scene would do a lot. I don't want anything massive, but having a little more character and getting some names for the characters would go a long way for me.
I do like the gameplay loop, but I do think it's a little too simple, especially when you have 3-4 possessions, and you really can't get caught. I think having traveling characters from other levels checking up/ asking questions to whoever you are possessing would be a fun hurdle to throw into the game to keep challenging the player even when they have most of the floor posesed and you could add scenes with them.
If you add any of these ideas or not I wishlisted this game and can't wait to purchase the game when it comes out.