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The strange door in the Blackbridge Grotto requires three Microchips to open in Blue Prince. We’ve already covered how to open the Blackbridge Grotto, but if you’re looking to get past that and crack the giant vault beyond — with a very special rare room as your reward — you’ll need to find the hidden microchips.
One microchip is already installed in the center of the Blackbridge Grotto, which means you’ll need to find two more to unlock the massive vault door. There are clues to discover as you dig deeper into the main game, but we’re just going to give you the straight answers. Here’s where to find the Microchips and finally solve the puzzle behind the Blackbridge Grotto door.
How To Open the Blackbridge Grotto Door
The Blackbridge Grotto is the server center and hub for all the computers in the house — and it’s the fourth permanent unlock room in the Grounds area. Learn how to unlock the Blackbridge Grotto with our complete guide here.
Once the Blackbridge Grotto is unlocked, you’ll be able to interact with the network admin terminal to the right of the large vault door or use the device with a microchip plugged into the circular center. There are three slots and getting all the microchips is deceptively simple.
- Microchip #1: The first Microchip is in the Blackbridge Grotto, plugged into the device in the center of the room. The microchip always spawns here, even if you move it.
- Microchip #2: Use the Sledgehammer to shatter the vases in the Entrance Hall. There’s a vase on both sides of the room. Break them, then look down at the shattered pieces — the Microchip will appear on the floor.
- Microchip #3: The last Microchip is in the West Gate area, to the right of the small bridge leading to the Outer Room door. Use a Shovel to dig up the green grass next to the bridge to collect the Microchip.
Once the Microchips are discovered they’ll be permanently unlocked. You don’t need the tools again — the Microchips will appear in the Entrance Hall and in the West Gate area.
What’s Behind the Grotto Door?
The Blackbridge Grotto door leads through a cavern and outside to a set of ancient ruins with a distant view of the town. The ruin has a permanent blueprint on the table in the center — this is one of the fabled blackprints. Collecting it will permanently add the blueprint to your draft roster. They’re extremely rare though and appear very infrequently when drafting rooms.
- Throne Room: Reclaim your crown!
- Contains a Sanctum Key.
The Throne Room is one of the locations where you’ll find a Sanctum Key — one of the extremely rare keys used to open the locked doors in the Inner Sanctum. The first (and most straightforward) Sanctum Keys is located in Room 46 — on your first visit, Room 46 leads to the ending. If you reach Room 46 a second time, you’ll find a Sanctum Key and other clues inside.
What Else Can You Do with Microchips?
Microchips have a secret secondary use. They can be used to unlock additional Laboratory experiments — this can be done at any time after unlocking the Apple Orchard.
- Get the Burning Glass contraption by combining the Looking Glass and Metal Detector items at any Workshop.
- Use the Burning Glass and Sledgehammer on the sundial in the Apple Orchard room. This allows you to move the section to solve a puzzle — line them up and use the microchips to create a satellite uplink.
Complete the steps at the Blackbridge Grotto — you can use the secret Network Admin passwords RibbJ or WithP (uppercase / lowercase matters) to gain maximum access to the network.
