MCio
by TwoTurtles
MCio gives AI research code a network interface into Minecraft, so an external Python program can send input and receive frames and game state.
What it does
Keyboard and mouse input arrives over ZeroMQ, and the mod returns video frames and game state to the connected program. A companion Python library named mcio_ctrl wraps this exchange in Gymnasium environments, which is the usual way training code reaches the game. Agents can connect and reconnect without restarting Minecraft, and the protocol is decoupled, so the client side can be swapped without changing the training code.
Two modes cover different work. Synchronous mode steps the game one tick at a time for fast training runs. Asynchronous mode lets a human and an AI act in real time in the same session. Resource packs can be loaded to vary the visuals across training environments. The author reports a real-time speed-up of about 13x on an M3 laptop, and the mod is said to work alongside performance mods such as Sodium.
MCio runs on Fabric for Minecraft 1.21.3 only. It requires Fabric API and is client-side only, so servers do not need it. The code is open source under the MIT License, and source, issues and a wiki are linked publicly. The latest file, 1.6.1+1.21.3, was released on 2026-02-15, after a first release on 2024-12-06.
Key features
Input and frame output
Keyboard and mouse commands arrive at the client, which returns rendered frames and game state through a ZeroMQ socket.
Gymnasium environments
A Python library named mcio_ctrl provides Gymnasium environments built on top of the network interface.
Synchronous and asynchronous modes
Synchronous mode suits fast training, while asynchronous mode supports real-time interaction between a human and an AI.
Resource pack variation
Resource packs can be used to produce varied visuals across training environments.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Reinforcement learning research
Researchers train agents that read frames and state from the game and send input back through the Gymnasium interface.
Human and AI play
Asynchronous mode lets a person and an AI share a live session, with both acting in real time.
Who it’s for: The mod suits AI researchers and developers who want a Minecraft environment their own code can drive. Players who only want gameplay changes will find no in-game content here.
Questions
Does MCio need Fabric API?
Does a server need MCio installed?
Which game version does MCio support?
Can MCio be used with other mods that change performance?
In the catalog
MCio is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 13,252 mods support Minecraft 1.21.3.
Similar mods
What the author says
MCio is a Fabric mod that exposes a network interface to Minecraft for AI research. It accepts keyboard/mouse input and sends back video frames and game state over ZeroMQ.
Official listing
- Modrinth page
- modrinth.com/mod/mcio
- Owner
- TwoTurtles
- Published
- 2024-12-06
- Updated on Modrinth
- 2026-02-15
- Facts verified
- 2026-10-15