A Curious Observatory questions

[Psychotronic]

I should tell you, there is no wrong door for that first key. No matter which door you open first, you can get to the end of the mansion and collect all the treasure. But no matter what you do, you'll miss a few rooms along the way. Actually, I suppose it's possible to see every room on a single play-through, but it would require a lot of work, and the mansion isn't really designed to let you do that.