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Megabonk Level Editor

Player guide

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How to install Megabonk Level Editor and play levels other people have made. For building or changing the mod itself, read modding-setup.md.

What this is

Section titled “What this is”

Megabonk Level Editor is an unofficial, fan-made mod. It is not made, endorsed or supported by the developer of Megabonk, and it is not part of Steam Workshop: there is no Subscribe button in Steam. The mod loads through BepInEx 6 IL2CPP and adds custom levels to Map Selection beside the built-in maps. Levels are shared as plain files you copy into the game’s folder.

The editor package contains no levels, third-party asset packs or music.

Before you start

Section titled “Before you start”
  • Install Megabonk through Steam and start it once.
  • Quit the game, and ideally Steam, before installing.
  • You need an internet connection the first time you launch the modded game. It downloads some tools and takes about half a minute while the screen stays black.
  • The mod supports the Windows build of Megabonk. On Linux and on a Mac, run that build through Steam Play (Proton) or Wine. Install those separately; the mod ZIP does not install Steam, Wine or the game.
  • Do not activate MelonLoader and BepInEx together. Keep a backup of an older setup and follow the loader rollback guide when switching between them.

Installing

Section titled “Installing”

The public Thunderstore release has not been published yet. For local testing, the package is built from source with task package:thunderstore; get that ZIP from its builder and import it through your manager’s local/custom-mod option. Its package identifier is Megabonk_Level_Editor.

  1. Select Megabonk in a compatible mod manager and create a clean profile.
  2. Install BepInExPack IL2CPP 6.0.788 and import the editor ZIP. Apply the profile to the game.
  3. Start the modded game. Check BepInEx/LogOutput.log for Megabonk Level Editor and MegabonkLevels mod initialized..
  4. Add a level as described below, then restart the game to see it on Map Selection.

On macOS, the tested setup is r2modmac 1.1.0 for managing files and plain Wine 11.18 for launching. Apply omits the BepInEx pack’s dotnet/ runtime, and its Play button did not launch the Wine-hosted game. Follow the package README’s Wine instructions for the runtime and winhttp override. For manual installation, see Installing by hand.

Disable the editor in the manager and Apply to remove it. Keep your levels, packs and music under UserData/; disabling the mod does not remove them.

Try Bramblecrown Hill

Section titled “Try Bramblecrown Hill”

Bramblecrown Hill is an example level supplied separately from the editor. Get levels/bramblecrown-hill.mblevel.json from the source repository or the person who shared the mod, then copy it into UserData/Levels/. It needs no extra packs or music. See Bramblecrown Hill for a tour of its five districts and a short move-rock, save-copy, replay tutorial.

The old standalone installer format is documented in player-installer.md as a legacy MelonLoader reference only; it is not compatible with the current BepInEx DLL.

Finding your levels folder

Section titled “Finding your levels folder”

Levels live in the game’s own folder, in UserData/Levels/:

  1. In Steam, right-click Megabonk, choose Manage, then Browse local files. That opens the game folder.
  2. Open UserData, then Levels. If either folder is missing, create it with exactly that name.

A level is a single file ending in .mblevel.json.

Playing a level someone shared

Section titled “Playing a level someone shared”
  1. Save the .mblevel.json file they sent you.
  2. Copy it into UserData/Levels/.
  3. Start Megabonk. The level appears on the Map Selection screen beside the built-in maps, under the title the author gave it.

If a level shows up but looks empty or as a placeholder, it needs an asset pack you do not have. The mod logs the missing pack’s name in BepInEx/LogOutput.log in the game folder as pack '<name>' is not installed. Ask the author for the pack, which is a folder to place in UserData/LevelPacks/.

A level can have a picture on the Map Selection screen: put an image with the same name as the level next to it, for example thps.png beside thps.mblevel.json.

Sharing a level

Section titled “Sharing a level”

Send the .mblevel.json file from your UserData/Levels/ folder, as a Discord attachment, a forum upload or by any other way you would send a file. If it has a picture, send that too. If your level uses an asset pack, say which one, because the person receiving it needs it as well.

Levels from other people are data files the game reads, not programs, but the mod itself is code from a third party. Install the mod only from someone you trust.