
Play Multiplayer in Single Player
A utility mod that makes singleplayer worlds behave more like lightweight multiplayer sessions by letting you switch identities before entering a world or…
⬇ Download on ModrinthMultiplayerLikeSingleplayer
Description
MultiplayerLikeSingleplayer is a powerful utility mod for Minecraft Forge 1.12.2 that transforms your singleplayer world into a lightweight multiplayer-like experience. Switch between multiple player identities in the same world, each with their own inventory, position, health, and progression—all without leaving your game or editing files manually.
How It Works (for the user)
- Before loading a world, you're presented with an identity selection screen showing all available player profiles for that world.
- Choose an existing identity or add a new offline username to create a fresh profile.
- The world loads with that player's saved data—inventory, location, XP, health, etc.
- Switch identities by simply leaving the world and choosing a different one when you re-enter.
- Each identity's progress is saved separately and automatically.
Additional Features
Multiplayer & LAN Enhancements
- Before joining any multiplayer server, you're prompted to choose an offline identity—perfect for testing on offline-mode servers.
- LAN worlds are forced to a fixed port (56567) and offline-mode for consistent local testing.
- A quick-join option detects localhost LAN servers and adds them to your server list temporarily.
Multi-Window Support (Multi-Process)
- Launch additional SUB windows as separate Minecraft processes from the main game.
- Window titles clearly indicate "Main Minecraft" and "SUB #N" for easy identification.
- Each SUB window runs independently and can be closed separately.
- Closing the MAIN window gracefully shuts down all SUB processes.
Permission Management
- Built-in permission editor lets you toggle operator (OP) status for any identity.
- Changes apply immediately to the running world.
- Use
/mlsp_reloadpermsto apply manual edits made to config files.
Identity Discovery & Management
- The mod automatically detects existing player data in your world and attempts to resolve real usernames from game files (
usercache.json,ops.json, etc.). - Unresolved names are given stable placeholders like
unknownplayer1. - All identities are stored in easy-to-edit config files (
mlsp_users.txtper world,mlsp_identities.txtglobally).
Who This Mod Is For
- Singleplayer players who want to maintain multiple characters in one world (e.g., a builder and a survival player).
- Server admins importing old server worlds for local analysis or migration.
- Modpack developers and map makers needing to test multiplayer scenarios alone.
- LAN party hosts wanting quick, repeatable local testing with multiple identities.
- Anyone who wants to simulate multiplayer interactions without setting up a full server.
Core Benefits
- No file editing – Switch identities through a simple GUI.
- Fully automatic – Player data is saved and loaded per identity without any extra steps.
- Lightweight – Runs alongside other mods without conflicts.
- Edition: Minecraft Java
- File type: .jar
- Minecraft versions listed: 1.12, 1.12.1, 1.12.2
- How to install: Install the matching mod loader (Forge, Fabric or NeoForge) for your Minecraft version. → Download the .jar. → Put it in the .minecraft/mods folder and launch that loader profile.
- Where to get it: Opens on Modrinth — not every file is mirrored on our own servers.
Install steps are the general flow for this file type — How to install Minecraft Java mods & modpacks walks through it step by step.
- Ships as MultiplayerInSingleplayer-1.0.0.jar — drop this file into the mods folder
- Download size: 69 KB
- Download link checked 8 Sept 2026 — working
These come from our own check of the pack file, not from the source page.
