How to Open Locked Doors in Core Keeper: Music Doors, Obsidian Doors and Puzzles

Summary

Each locked door opens a different way

Music note doors: play a melody
Doors with a music note on them open when you play a specific melody on an instrument nearby.
Doors that need an item
Some doors open when you approach holding a Glow Tulip; others need a Admin Key or Obsidian Key inserted.
Electric doors and puzzles
Electric doors and electric drop gates open when powered. In puzzle rooms, you solve the mechanism to send power to them.

Types of locked doors and how to open them

Door	How to open	Where
Door with a music note	Play the right melody on an instrument nearby (melodies)	Scenes in each biome
Glow tulip door	Walk up to the door holding a Glow Tulip	Chipped Blade Temple, Sealed 3-Wing Temple, Sealed Chapel
Admin key door	Insert the Admin Key into the door	Glyph Parchment Treasury
Locked Obsidian Door	Insert the Obsidian Key (the key is used up and it becomes a normal obsidian door). Breaking it does not open it (you just pick it up, still locked). Ranged attacks do not affect it.	Puzzle scenes
Electrical Door, Electrical Drop Gate	Opens when powered. Send power with a lever, pressure plate, sensor or a puzzle mechanism	Puzzle scenes and more
Excavation Doorway	Insert the Brood Void Neuron to open it and reach Breaker's Reach. The neuron cannot be taken back out	Breaker's Reach
The Great Wall	Move the three statues around the Core (Glurch, Ghorm, Malugaz), then hold your hand to the wall	See the boss order

Normal doors (wooden doors and so on) open and close when you interact with them (door types). For the list of keys, see key types.

Music note door melodies (doors opened with an instrument)

A door with a music note drawn on it opens when you stand right next to it and play a specific melody on an instrument. Any instrument works (such as the Ocarina).

The melody depends on where the door is. With the default keyboard layout (Z to M play C to B), the commonly known melodies are "C N M B C N M" for the Undergrounds door, "N C N C X" for the Clay Caves door and "B B N V B X V B" for the Forgotten Ruins door.

List of puzzle rooms

These scenes are puzzle rooms whose doors open once you solve the mechanism.

Mechanics from the Core Keeper Wiki (Fandom) pages "Locked Obsidian Door", "Excavation Doorway" (CC BY-SA 3.0), summarized in our own words (not confirmed in the game files).

Unless a note on the page says otherwise, numbers are read from the game files of Core Keeper 1.3.0.6 (prefabs, configuration files, drop tables and the game's program) and calculated by this site, including upgraded (per-level) values, sell prices and mana costs. Names and descriptions are the game's official English text. Only reinforcing materials, minion and pet attacks and some food values are based on the Core Keeper Wiki (Fandom) data (CC BY-SA 3.0). Core Keeper and its images are © Pugstorm. This is an unofficial fan site.