CraftUtopia: A LLM-based Multi-Agent System for Collaborative Construction in Minecraft

LLM-based multi-agent construction is a growing research area but prior works still suffer from low success rates for construction, reliance on predefined templates, and poor scalability as the number of agents increases. To address these challenges, we present CraftUtopia, an LLM-based multi-agent system (MAS) that constructs 3D structures in Minecraft from a single 2D reference image. CraftUtopia operates in two stages: Design, which converts the image into a Minecraft-compatible 3D blueprint, and Build, which decomposes the blueprint into spatially disjoint subtasks for parallel execution. CraftUtopia scales efficiently via two mechanisms: (i) hierarchical coordination, which organizes agents in a manager-foreman-worker hierarchy to separate responsibilities, and (ii) skill acquisition, which distills recurring action sequences into a shared skill library to reduce repeated LLM replanning. Across three representative builds, CraftUtopia achieves 100% success over five trials using only 2D inputs, scales effectively with more workers, and exhibits emergent human-like behaviors. A full demo is available at: https://github.com/craftutopia-demo/CraftUtopia.