Factorio Learning Environment (FLE) is a novel framework built on the game Factorio, used to evaluate the capabilities of large language models (LLMs) in long-term planning, program synthesis, and resource optimization. As LLMs gradually saturate existing benchmark tests, FLE provides a new open-ended evaluation approach. Its importance lies in enabling researchers to gain a more comprehensive and in-depth understanding of the strengths and weaknesses of LLMs. Key advantages include open-ended challenges with exponentially increasing difficulty, and two evaluation protocols: structured tasks and open-ended tasks. This project was developed by Jack Hopkins et al., released as open source, free to use, and aims to promote research by AI researchers on the capabilities of agents in complex, open-ended domains.