Blue Prince: Mirror Room Puzzle Guide
Image Credits: Dogubomb, Blue Prince
The Mechanarium, or mirror room, is like a mechanical spider with eight legs—each one being a door. Problem is, most of those doors are locked unless you meet some very picky requirements. If you want to fully open it up and grab the good loot (yes, there's a Sanctum Key in there), here's how to play the room’s weird little game.
First: What Is the Mechanarium?
It’s a special room you can only get from a blueprint found in the Underground.
Once unlocked, it can randomly appear in your drafts—if the game feels like it.
It has eight doors total, but only one starts open—the entrance.
The goal? Open all the other seven.
The Basic Requirement
To get all the doors, the game checks how many gear-type rooms you’ve drafted before you pick the Mechanarium. These rooms have gear icons and include:
Workshop
Utility Closet
Pump Room
Boiler Room
Laboratory
Security Room
Aquarium (only if upgraded with the Electric Eel)
If you have 7 or more of those rooms drafted, the Mechanarium will show up fully unlocked—with all doors available.
Solution 1: Chamber of Mirrors
Drafting seven gear rooms in one run is hard. Enter the Chamber of Mirrors.
This room’s effect makes it possible for already-used rooms to reappear in the draft pool.
That means you can double up on gear rooms: two Workshops, two Pump Rooms, etc.
It’s rare, but very useful.
Get seven gear-type rooms, then draft the Mechanarium and voilà, all doors should be accessible.
Tip: You can also craft a Powered Electromagnet in the Workshop to increase the odds of gear rooms showing up.
Solution 2: Wall It Off Like a Pro
Here’s a sneaky trick:
The game checks how many open paths surround the slot where you place the Mechanarium.
Fewer open paths = fewer gear rooms required.
How to exploit that:
Before placing the Mechanarium, wall off the space around it by surrounding it with rooms that have no connecting paths.
If you can block the 3 main directions (north, east, west), the game only counts the 4 diagonal doors instead of all 7.
So now you only need 4 gear rooms drafted beforehand instead of seven.
Yes, this is technically cheating. No, we don’t feel bad.
Rewards for Solving the Puzzle
If you open all 8 doors, here’s what you’ll find:
One door always has a lever tied to the Antechamber puzzle.
The final, last-to-open door always has a Sanctum Key.
The rest? Random loot like gems, coins, or other goodies.
Final Blurb
The Mechanarium is one of those “wait, do people actually figure this out?” kind of rooms. But with enough gears, mirrors, and mild trickery, you can crack it wide open. Just remember: if the RNG isn’t kind, your eight-door dreams might have to wait till the next run. Or the next lifetime.
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