MultiplayerLikeSingleplayer

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_reloadperms to 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.txt per world, mlsp_identities.txt globally).

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.

Play Multiplayer in Single Player