Play Multiplayer in Single Player
by Itamio
Play Multiplayer in Single Player lets a single-player world behave like a lightweight multiplayer session, with a separate identity for each player who joins it.
What it does
Before a world loads, a selection screen lists the identities available for it. A player can pick an existing one or create a fresh offline username. The world then loads with that identity's saved data, including inventory, location, experience and health. Leaving the world and choosing another identity keeps each one's progress saved separately and automatically.
The mod also covers joining servers. Before a player connects to a multiplayer server, a prompt asks for an offline identity, which suits testing servers that run in offline mode. It is published for Forge only, for 1.12 – 1.12.2, with 2.0.0 for 1.12.2 as the latest file.
Key features
Identity selection on world load
Each world offers a list of identities before it loads, and a new offline username can be created at that point.
Separate progress per identity
Inventory, position, health and experience are stored for each identity and restored when that identity is chosen again.
Multi-window sessions
Extra SUB windows start as separate Minecraft processes, titled by number, and closing the MAIN window shuts down the SUB processes.
Operator status editor
A built-in permission editor toggles operator status per identity, and changes apply to the running world immediately.
Automatic identity discovery
Existing player data in a world is matched to real usernames where possible, and unresolved names get stable placeholders such as unknownplayer1.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
How it compares
Offline Whitelist - Username-Based is a Forge option for 1.18.2 that is server-side only and uses the CC-BY-1.0 license; it is not open source. OAuth is open source under the GNU Lesser General Public License v3.0 or later, covers 1.7.10 – 1.20 on Fabric and Forge, and is client-side only. RuSureQuit is open source under the MIT License, is client-side only and spans 1.20 – 1.21.10 on Fabric, Forge and NeoForge.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Play Multiplayer in Single Player | Forge | 1.12 – 1.12.2 | Client or server, optional | 2026-03-01 |
| Offline Whitelist - Username-Based | Forge | 1.18.2 | Server-side only | 2024-01-28 |
| OAuth | Fabric and Forge | 1.7.10 – 1.20 | Client-side only | 2023-06-09 |
| RuSureQuit | Fabric, Forge and NeoForge | 1.20 – 1.21.10 | Client-side only | 2025-12-20 |
Questions
Which loader does Play Multiplayer in Single Player need?
Does the server need this mod installed?
Where are identities stored?
Can operator status be changed while the game runs?
In the catalog
Play Multiplayer in Single Player is one of 36,990 Utility mods on ModsFinder, and one of 14,575 Utility mods for Forge. 2,920 mods support Minecraft 1.12.2.
More from Itamio
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What the author says
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…
Official listing
- Modrinth page
- modrinth.com/mod/play-multiplayer-in-single-player
- Owner
- Itamio
- Published
- 2026-03-01
- Updated on Modrinth
- 2026-03-01
- Facts verified
- 2026-10-15