How To Solve The Mechanarium Puzzle In Blue Prince

Planning to solve the Mechanarium Puzzle in Blue Prince? The goal is to ensure that the last door can be accessed, and that can only be done if you place down the correct rooms all over the house. There's also a neat workaround in case you're having trouble with this task. Likewise, please be reminded that this guide contains minor spoilers.

How to complete the Mechanarium Puzzle in Blue Prince - Mechanarium Eight Doors guide

The Mechanarium is a special room since it's not available by default. Instead, it comes from a Floorplan, which you can only obtain in the Underground. Once you've acquired this blueprint, it has a chance of appearing as an option during your runs.

As for the Mechanarium Puzzle in Blue Prince, it's actually fairly tough challenge due to the strict requirements. Basically, the Mechanarium has eight doors (including the entrance where you came in). You need to ensure that you have access to the extra doors, as the last one nets you a cool reward.

Important: To ensure that all the Mechanarium's doors appear, you must draft the Mechanarium after you have placed at least seven gear-type rooms. The gear-type rooms include the Workshop, Security, Utility Closet, Laboratory, Pump Room, Boiler Room, and the Aquarium (provided that it has the Electric Eel upgrade).

Tips and tidbits about the Mechanarium and related items

Note 1: The Mechanarium is a gear-type room, though it only counts as the entrance door. If you draft it with no other gear-type rooms in the manor, then you won't see any door besides the entrance itself.

Note 2: You can craft the Powered Electromagnet item via the Workshop. This increases the chance that gear-type rooms appear in the selection pool. If you have the Powered Electromagnet and you don't have enough steps to draft all the rooms, then you can store it in a Coat Check and retrieve it on a different day.

Note 3: Likewise, you may use the Gear Wrench item, which appears very infrequently in the manor. If it's in your inventory, you'll be able to change the rarities of any gear-type room that you draft. If many gear-type rooms have "commonplace" rarity, then your drafting process for your Mechanarium run should be much smoother. (Thanks to JackBranagan in the comments section for the tip.)

Solution 1: Chamber of Mirrors

You need to have seven gear-type rooms early on just to ensure that the Mechanarium's doors are all accessible later. That's a difficult task since you're not always guaranteed to see all the aforementioned rooms.

One "trick" that you can do is to draft the Chamber of Mirrors, which is quite rare in and of itself. The Chamber of Mirrors' effect allows for duplicates of rooms to reappear in the selection pool. So, technically, you can draft two Workshops, two Utility Closets, and so on. Once you have seven gear-type rooms placed down, pray to the RNG gods that the Mechanarium also shows up as an option so you can draft it.

Note: Ideally, you should place several gear-type rooms early, followed by the Chamber of Mirrors. This ensures that the duplicates in the draft pool are predominantly gear-type rooms as well. However, if you place down the Chamber of Mirrors later in your run, then duplicates of every type of room will appear in the pool. This significantly impacts the RNG.

Solution 2: Sealed-off pathways

The other option is a bit "gamey" but it's also lets you partially circumvent the requirements. Here's the gist:

• Before you place down the Mechanarium, the game detects how many open pathways there are in each slot in the manor grid.
• If we don't count the entrance where you came in, you need seven gear-type rooms because:
  • There are three remaining cardinal directions.
  • There are four diagonal segments--i.e. the extra rooms.
• However, if you block off the remaining cardinal directions, you also decrease the number of required gear-type rooms since there's no way for those doors to be created.
• Basically, you can create a path around the slot where you'd want the Mechanarium to appear. If these paths are blocked off already--i.e. you place rooms with walls adjacent to the Mechanarium's eventual slot--then they won't count toward the overall tally.

In a way, if you can block off the remaining three cardinal directions, and if you can place the Mechanarium in the center of that section, then you'll only need four gear-type rooms.

Solution 3: Aquariums... lots and lots of Aquariums

There's one more viable solution for the Blue Prince Mechanarium Puzzle, and the suggestion comes from JamieLovesMCR in the comments section. It involves spamming a lot of Electric Eel Aquariums in the manor. This process requires a bit of work, but it can really help you in the long run:

• Collect Upgrade Disks until one of them lets you choose an Aquarium upgrade. Pick the Electric Eel perk--it has the same function as a Boiler Room and it also counts as a mechanical/gear-type room.
• Along the way, make sure you obtain all Microchips so you can place them in the Sundial. This unlocks the Satellite Dish and the data packet.
• Use a terminal to download the data packet. It adds more causes/triggers and effects for your Laboratory experiments. When customizing packets, ensure that you have these options:
  • Cause/trigger: "Each time you draft an upgraded floorplan"
  • Effect: "Add +3 Aquariums to today's draft pool"

Once everything has been set up, continue playing until you get the Laboratory experiment that has the above cause/effect options. Since the Electric Eel Aquarium counts as an upgraded floorplan, you will keep seeing it as a drafting option. In the end, you can have so many Electric Eel Aquariums that opening the Mechanarium's doors shouldn't be a hassle.

Mechanarium Puzzle rewards

The extra doors in the Mechanarium have random rewards, though one nook will always have an alternate lever for the Antechamber. Likewise, if you manage to complete the Blue Prince Mechanarium Puzzle--i.e. all four diagonal section doors are accessible--then the last door that you open will automatically contain a Sanctum Key.

You can learn about these unique items in our Sanctum Key locations guide. Also, you might want to take a look at another tricky puzzle in the Closed Exhibit.