Cobalt Core Archipelago

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A Cobalt Core mod for the Archipelago multi-game randomizer system.

  • Version: 1.2.1
  • Archipelago version: 0.6.6
  • Cobalt Core version: 1.2.9
  • Nickel Version: 1.20.3+
  • Nickel API Version: 1.5.7
  • (Optional) Custom Run Options version: 1.5.3

The mod may work with other versions, but has not been tested on them.

Associated APWorld repository (direct link to the relevant folder/branch)

Current Status (June 2026)

The mod is stable. I will keep an eye out for small bugs and suggestions, but I'm taking a break from the mod for the moment. I expect to start working on new features again within the year.

If you encounter any issues while playing, please ping me on Discord (saltyisaac) in the Cobalt Core channel on the Archipelago Server, or make an issue on this repository. (Please ensure that no one else has reported it yet, to the best of your ability!)

I am also looking for feedback on how much fun the mod is to play, balance details and other kinds of suggestions. Look at the Planned Features and Known Issues sections for more details.

I mostly did this for fun, so I make no promises as to how responsive I will be nor how long I will keep working on this mod. If I were to become inactive, I give my blessing to anyone who wants to fork the repository.

What is an "Archipelago Randomizer", and why would I want one?

Let's say I'm playing Cobalt Core, and my friend is playing Ocarina of Time. I may encounter a card saying it unlocks my friend's Hookshot. When I play it, it allows them to reach several OoT chests they couldn't before. In one of those chests they find Drake, meaning I can now select her when starting a run and find new cards and artifacts I couldn't before. One of these artifacts unlocks my friend's Ocarina when picked up. This continues until we both find enough of our items to finish our games.

In essence, a multi-game randomizer system like Archipelago allows a group of friends to each bring whatever games they want (if they have an Archipelago mod) and smush them all together into one big cooperative multiplayer experience.

What this mod changes

On default settings, you will start with three randomly chosen characters and a randomly chosen ship. Starting cards for each character are randomized as well. Aside from the starting cards, most of the cards and artifacts you will find will be unplayable until they are unlocked by you or another player.

Usual character and ship unlock conditions are removed. In order to unlock ships, characters, cards, artifacts, or items for other games, you will find special cards and artifacts which unlock an item when played. Which items you find will depend on which characters you have in your run.

The goal is to accumulate a certain amount of memories (1 for each character by default), which unlocks the Future Memory sequence. Finishing this sequence completes the game.

There are more details in the YAML options file as well as in the in-game mod settings (such as Deathlink).

Installation

Prerequisites and dependencies

  • Make sure Cobalt Core is installed in the current version.
  • Install Nickel. You can use this setup guide.
  • Run the nickel launcher at least once and close the game.
  • Optionally, you can also install Custom Run Options (only available through NexusMods). It will allow you to start with less than 3 characters.
  • Install the core Archipelago tools (at least version 0.6.4, but preferably the latest version) from Archipelago's GitHub Releases page. On that page, scroll down to the "Assets" section for the release you want, click on the appropriate installer for your system to start downloading it (for most Windows users, that will be the file called Setup.Archipelago.X.Y.Z.exe), then run it.
  • Go to the Releases page of this repository and look at the latest release. There should be three files: A .zip, an .apworld and a .yaml. Download all three.

Archipelago tools setup

  • Go to your Archipelago installation folder. Typically, that will be C:\ProgramData\Archipelago.
  • Put the Cobalt.Core.yaml file in Archipelago\Players. You may leave the .yaml unchanged to play on default settings, or use your favorite text editor to read and change the settings in it.
  • Double-click on the cobalt_core.apworld file. Archipelago should display a popup saying it installed the apworld. Optionally, you can double-check that there's now an cobalt_core.apworld file in Archipelago\custom_worlds\.

I've never used Archipelago before. How do I generate a multiworld?

Let's create a randomized "multiworld" with only a single Cobalt Core world in it.

  • Make sure Cobalt.Core.yaml is the only file in Archipelago\Players (subfolders here are fine).
  • Double-click on Archipelago\ArchipelagoGenerate.exe. You should see a console window appear and then disappear after a few seconds.
  • In Archipelago\output\ there should now be a file with a name similar to AP_95887452552422108902.zip.
  • Open https://archipelago.gg/uploads in your favorite web browser, and upload the output .zip you just generated. Click "Create New Room".
  • The room page should give you a hostname and port number to connect to, e.g. "archipelago.gg:12345".

For a more complex multiworld, you'd put one .yaml file in the \Players folder for each world you want to generate. You can have multiple worlds of the same game (each with different options), as well as several different games, as long as each .yaml file has a unique player/slot name. It also doesn't matter who plays which game; it's common for one human player to play more than one game in a multiworld.

Installing and running the Cobalt Core mod

  • Extract the .zip file you downloaded at the end of the Prerequisites section in the ModLibrary folder inside your Nickel folder.
  • Run the game using the Nickel Launcher. Cobalt Core mods only work when the game is run this way.
  • If the mod is correctly installed, the game will always start on the save selection screen. If it does not, there was an issue during installation.
  • You cannot run already-existing saves with the Archipelago mod. These will be marked with a crossed AP icon and will not be clickable. Click on an empty save (delete one if necessary), and you will be prompted for your connection info: hostname, port number, slot name and password.
  • Use the hostname and port number from the previous section. Your slot name will be CAT1 by default, but you can change it in Cobalt.Core.yaml. If you didn't set a password you can leave it empty.
  • Press "Connect", and, if everything went right, you should be in the main menu. You are now connected and ready to start playing with other people!

Mods that are supported / known to work with AP

Will other mods be supported?

I don't know for sure yet. If there are compatibility issues with "utility" or "quality of life" type mods, I will try my best to fix them. However, the AP protocol cannot support added characters or cards as a generic thing, as far as I am aware. They would have to each be added individually. If someone can work out a solution for this we can discuss it, but if it proves to be too big of an undertaking I will probably not do it myself.

Planned features (no promises!)

  • Actual dialogue for the additional Books and CAT memories.
  • Additional in-combat dialogue between characters when getting new items from other players, or unlocking items for other players. Lots of dialogue if possible!
  • Potentially additional cards or artifacts which give the game more interactivity with the multiworld.

Known issues

  • Using Nickel's import function to import a save from the vanilla game will immediately throw you onto the main menu without connecting to a host. This is not supported and will probably crash quickly, but it's fine as long as you close the game immediately.

Credits

  • Mufflebuns: Writing for CAT's announcements
  • popouleto: Linkboros card art and help with the card frames
  • Shockah for making Nickel and helping me with various issues
  • rft50 for making the DemoMod that eased me into modding Cobalt Core considering I had no idea what I was doing
  • All players who have tested the mod and given feedback, notably JyGein and Exuno
  • Ixrec for making the great Nine Sols AP mod whose code helped me figure out how an AP integration is supposed to work considering I also had no idea what I was doing on that front either
  • Landmaster who first started a Cobalt Core Archipelago project which was never finished but can be found here
  • All the people in the CC modding community who answered my many questions
  • All the Archipelago contributors for making this frankly absurd project
  • Everyone at Rocket Rat Games for making a very cool and cute game that is not only very fun to play but also very fun to mod