The main goal of Blue Prince is to find room 46, and the key to this is opening up the Antechamber. Even if you reach Rank 9, and have a door connecting to the Antechamber, you won’t be able to enter ...

As mentioned, you'll first need to remove all of the Tunnel Crates to even access the door. Then, you need to open several doors before accessing the Blue Door. Here's how to open the first six doors ...