Very nice! I found every red piece and painting, but I still got the B ending... Plus, I honestly expected a confrontation with the Baron, but there kinda wasn't one. So... how do we get the endings exactly? And how many decorations are there?
Oh, also, there's a note you can't read in the basement. Some notes also seem to repeat, as well as the Baron's dialogue once, but I think these are just there in case we missed the first ones. Oh, and the dialogue regarding the apartment for Snowflake said that Chat "found a place for rent on the (insert here) floor", and he says the guy is named Loyd but he's actually Gary, so... that does feel a bit unfinished, hehe. I would also talk about how some lines let us know the Baron's name is actually Blake before the actual reveal, but that's honestly up to you to see fit with how the story goes.
One last problem I encountered - the elevators don't reset when you use them. So, if you use one to reach a higher floor, then teleport back to a lower floor... the elevator won't go down, and it will in fact be blocking the path upwards if we fly through the elevator shaft.