Core Keeper NPC houses need to be built properly if you want the friendly little merchants to live at your base. As you explore the underworld of Core Keeper you'll find powerful boss monsters, and when you defeat them you'll gain access to special items that can be used to summon wandering merchants to come live with you.
There are three known NPCs merchants in Core Keeper, and two of them need houses: the Slime Merchant and the Caveling Merchant (the third, the Spirit Merchant, does not need a house—more on this below). Having merchants close by your base is useful because they'll buy any valuables you find in exchange for ancient coins and sell items you may need. It's also nice just to have a little company at your base, especially if you're playing solo.
There are a few rules you need to follow to properly build a house for an NPC merchant and specific items you need to place in their rooms or they won't move in. Below, we'll go over the different merchants in Core Keeper and how to lure them into becoming your roommates.
How to build an NPC house
Core Keeper NPC house: How to build one
Here's what you'll need for each merchant you want to occupy your base:
- A walled room no bigger than 8x8
- Wooden doors
- A bed that a player has not slept in
- The merchant's summoning item
Note that the room should be no bigger than 8x8 or the merchant won't move in. Each merchant's room should also have a wooden door—at the moment, there appears to be a bug so stone doors will prevent the merchant from moving in.
You will also need to place a bed in the room for the merchant. Once placed, players should not sleep in this bed or the merchant will begin wandering away from your base. If you do sleep in the bed, remove it and replace it, which will draw the merchant back.
Finally, you'll need to place each merchant's summoning item in their room (except the Spirit Merchant, which can be placed anywhere). The items are:
- Slime Merchant: Slime Oil
- Caveling Merchant: Mysterious Idol
Once you've built the room and placed the bed and summoning item on the floor (not on a pedestal), travel away from your base for a few seconds. Once you've moved a few screens away from your base, return and the merchant will appear in their room.
Note: With the door closed, the merchant should remain in their room. With the door open, they may leave the room and wander around nearby. Don't worry, they won't completely leave the area and will stay pretty close to their room.
How to find merchants
Core Keeper NPC merchants: How to find them and what they sell
You gain access to the merchants by defeating Core Keeper's first three bosses. Here's each merchant, the boss you need to defeat, their summoning item, and what they sell. Note that merchants initially do not have every item in stock and their inventories may increase as you progress.
| Merchant | Boss | Summoning Item | Shop Items |
| Slime Merchant | Glurch the Abominous Mass | Slime Oil | Slime, wood, fiber, copper ore, tin ore, iron ore, gold ore, larva meat, golden larva meat |
| Caveling Merchant | Ghorm the Devourer | Mysterious Idol | Caveling bread, iron chunk necklace, flintlock musket, giant slime summoning idol, ghorm summoning idol, hive mother summoning idol, mechanical part, ancient gemstone, rune parchment |
Spirit Merchant
The Spirit Merchant
The Spirit Merchant is a bit different. After defeating the Hive Mother, you can craft the Ancient Hologram Pod at the Hive Mother statue at the Core. It does not need a room or a bed (because the Spirit Merchant is a hologram).
The Ancient Hologram Pod is a workbench that summons the Spirit Merchant, allowing you to craft additional items.
