4B Decision Model Mica Mines a Diamond Pickaxe in 26 Steps on First Real-Minecraft Run
Top-Evidence174 · reddit · 2026-09-28
A developer showed Mica v0.1, a 4B decision model, completing real Minecraft (not a sim) from an empty inventory: 26 decisions, 8 minutes of game time, diamond pickaxe — on the first run after reworking the harness, at 108 ms per decision.
At each step the model reads game state as text (inventory, nearby blocks, health, last action) and picks from candidate commands; a Mineflayer bot with Mindcraft skills executes. It already knows the nearest diamond location. A highlight: at step 14 it chose to mine coal instead of burning planks (0.69 vs 0.31), smelting all three iron at once — the better call.
The author stresses this isn't a 4B model playing Minecraft alone, but proof small models can read the state and make good calls behind a bot. The harness will be open-sourced with chat-based commands, and v0.5 (plus a lightweight Distill Laya build) targets 4B JEV-class top performance and possibly the Ender Dragon.
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