⚙ Factorio Learning Environment

Factorio Learning Environment (FLE) is an open source framework for developing and evaluating LLM agents in the game of Factorio.

FLE tests agent capabilities in long-term planning, program synthesis, and resource optimization against a set of exponentially scaling challenges, ranging from basic automation to complex factories processing millions of resources per second.

We provide two settings:

1. Lab-play: Eight structured tasks with fixed resources.
2. Open-play Unbounded task of building the largest possible factory on a procedurally generated map.

Our results demonstrate that models still lack strong spatial reasoning. In lab-play, we find that while LLMs exhibit promising short-horizon skills, they are unable to operate effectively in constrained environments, reflecting limitations in error analysis. In open-play, while LLMs discover automation strategies that improve growth (e.g electric-powered drilling), they fail to achieve complex automation (e.g electronic-circuit manufacturing).

Quick Links

• Installation
• Environment
• Agents
• Tools
• Project Structure
• Benchmarks
• Contributions

Installation

Prerequisites

• Factorio (version 1.1.110)
• Docker
• Python 3.10+

Quickstart

1. Clone the repository:

git clone https://github.com/JackHopkins/factorio-learning-environment.git
cd src
pip install -e .

2. Set up Factorio client:

• Purchase Factorio from the official website or on Steam.
• Downgrade to version 1.1.110:
  • Steam: Right-click Factorio → Properties → Betas → Select 1.1.110

3. Launch FLE Docker server:

# Start Docker daemon
sudo systemctl start docker

# Build Docker image
cd cluster/docker
docker build -t factorio .

# Run a single server
cd ../local
docker-compose -f docker-compose-1.yml up -d

4. Activate server:

• Open Factorio client
• Navigate to Multiplayer
• Connect to localhost:34197 (default) or your configured address in Docker.

4. Run Eval:
   1. Open Play:
   2. Tasks:

Environment

FLE is an agent evaluation environment built on the game of Factorio, a popular resource management simulation game.

Agents interact with FLE by code synthesis through a REPL (Read-Eval-Print-Loop) pattern:

1. Observation: The agent observes the world through the output streams (stderr/stdout) of their last program.
2. Action: The agent generates a Python program to perform their desired action.
3. Feedback: The environment executes the program, assigns variables, add classes/functions to the namespace, and provides an output stream.

Action # 1. Get iron patch and place mining drill drill = place_entity( entity=Prototype.MiningDrill, position=nearest(Prototype.IronOre)), direction=Direction.NORTH ) # 2. Add output storage chest = place_entity_next_to( entity=Prototype.IronChest, reference_position=drill.drop_position, direction=Direction.SOUTH ) # 3. Verify automation chain and observe entities sleep(10) # Sleep for 10 seconds assert drill.status == EntityStatus.WORKING print(get_entities())

Feedback >>> [ BurnerMiningDrill(fuel=Inventory({'coal': 4}), >>> name='burner-mining-drill', >>> direction=Direction.DOWN, >>> position=Position(x=-28.0, y=-61.0), >>> energy=2666.6666666667, >>> tile_dimensions=TileDimensions(tile_width=2.0, tile_height=2.0), >>> status=EntityStatus.WORKING, >>> neighbours=[Entity(name='iron-chest', direction=DOWN, position=Position(x=-27.5 y=-59.5)], >>> drop_position=Position(x=-27.5, y=-59.5), >>> resources=[Ingredient(name='iron-ore', count=30000, type=None)]), >>> Chest(name='iron-chest', >>> direction=Direction.UP, >>> position=Position(x=-27.5, y=-59.5), >>> energy=0.0, >>> tile_dimensions=TileDimensions(tile_width=1.0, tile_height=1.0), >>> status=EntityStatus.NORMAL, >>> inventory=Inventory({'iron-ore': 75}))]

Agents are provided with the Python standard library, and an API comprising tools that they can use.

Tools are functions that perform a game action and return a typed object (e.g an Inventory), which can be stored as a named variable in the Python namespace for later use.

The namespace acts as an episodic symbolic memory system, and saved objects represent an observation of the environment at the moment of query.

This enables agents to maintain complex state representations and build hierarchical abstractions as the factories scale.

Agents observe stdout and stderr - the output streams of their program. Agents may intentionally choose to print relevant objects and computations to the output stream to construct observations.

Mistakes in the code or invalid operations raise typed exceptions with detailed context that is written to stderr.

This enables agents to reactively debug their programs after execution, and proactively use runtime assertions during execution to self-verify their actions.

Agents are able to enhance their internal representation of the game state by defining:

1. Utility functions for reuse throughout an episode, to encapsulate previously successful logic
2. Classes in the namespace to better organize the data retrieved from the game.

Agents

The Factorio Learning Environment provides a straightforward agent architecture for developing and evaluating AI models that can play Factorio.

Agents operate in episodes, with each step involving observation, planning, and action execution through Python code synthesis. The agent maintains state through a conversation history that includes its actions (assistant) and the stdout/stderr from the environment (user). At each step, agents generate Python code policies that are executed in the environment.

Anatomy of an Agent

Agents live in agents, and implement an abstract base class (AgentABC) that defines the core interface for interacting with the environment.

The abstract base class defines two methods that all agents must implement:

# Generates the next action based on conversation history and environment response (including score / achievements etc).
step(conversation: Conversation, response: Response) -> Policy:

# Handles cleanup when an episode terminates, i.e for reporting results etc.
end(conversation: Conversation, completion: CompletionState) -> None:

Our default agent is BasicAgent, which incorporates some basic mechanisms for managing context over long (+1000 step) runs:

1. Every 32 steps, the all older interactions are summarised into a report in the system message.
2. Conversations are clipped to remain under 200k characters (~87k tokens).
3. We strip out all historical observations of game entities, as this both fills up the context, and confuses the agent.

We include some basic utilities for calling different LLMs (agents/utils/llm_factory.py), for formatting the conversation history (agents/utils/formatters/conversation_formatter_abc.py), and for parsing responses into valid Python (agents/utils/parse_response.py)

Minimal Agent Example

# ./agents/minimal_agent.py

class MinimalAgent(AgentABC):
    """
    This is a minimal Agent implementation, which takes the current conversation (including the most recent response)
    and generates a simple Python code policy to execute the next step.
    
    Note: This will blow up context length on longer runs, without some context pruning/management.
    """
    def __init__(self, model, system_prompt, *args, **kwargs):
        super().__init__(model, system_prompt, *args, **kwargs)
        self.llm_factory = LLMFactory(model)
    
    @tenacity.retry(
       retry=retry_if_exception_type(Exception),
       wait=wait_exponential(multiplier=1, min=4, max=10)
    )
    async def step(self, conversation: Conversation, response: Response) -> Policy:
        # Generate and return next policy
        response = await self.llm_factory.acall(
           messages=self.formatter.to_llm_messages(conversation),
           n_samples=1,  # We only need one program per iteration
           temperature=self.generation_params.temperature,
           max_tokens=self.generation_params.max_tokens,
           model=self.generation_params.model,
       )
        
       # Parse LLM response into a Policy object
       policy = parse_response(response)
       if not policy:
           raise Exception("Not a valid Python policy")

       return policy

    async def end(self, conversation: Conversation, completion: CompletionResult):
        pass

Tool Documentation

Agents interact with the game using tools, which represent a narrow API into the game.

Anatomy of a Tool

Tools live in env/src/tools, and are either admin tools (non-agent accessible) or agent tools (used by the agent).

A tool requires 3 files:

1. agent.md: The agent documentation for the tool, including usage patterns, best practices and failure modes.
2. client.py: The client-side implementation, which is a Python class that can be invoked by the agent.
3. server.lua: The server-side implementation, which handles most of the logic and heavy lifting.

---
config:
  layout: fixed
  flowchart:
    defaultRenderer:
        elk
---
flowchart LR
    A("fa:fa-comment-dots Agent")
    subgraph s1["Learning Environment"]
    
        B("fa:fa-code Interpreter")
        n1("client.py")
    end
    subgraph s2["Factorio Server"]
        E1["fa:fa-shapes server.lua"]
        F("fa:fa-cog Factorio Engine")
    end

    A -- Synthesises Python --> B
    B -- Invokes --> n1 
    n1 -. Exceptions .-> B
    n1 -. Objects .-> B
    n1 --Remote TCP Call--> E1
    E1 -- Execute --> F
    
    F-. Result .-> E1
    E1 -. TCP Response .-> n1
    B -. Observation .-> A

Loading

Creating a custom Tool

1. Create a new directory in env/src/tools/agent, e.g env/src/tools/agent/my_tool
2. Add a client.py file, which should contain a class inheriting Tool and implementing a __call__ function to treat the class as a callable function. The method signature should contain type annotations. This function must call self.execute to invoke the server-side logic.
3. Add a server.lua file, containing a function structured like global.actions.my_tool = function(arg1, arg2, ...). This file should invoke the Factorio API to perform the desired action, and return a table that will be serialized and sent back to the client.
4. Add an agent.md file, which should contain a markdown description of the tool. This file will be used by the agent to understand how to use the tool

Next time you run an eval, the tool will automatically be available to the agent and documented in the agent context.

5. (Optional) Create a test suite in env/tests/actions for your new tool.

Core Tools

Tool	Description	Key Features
inspect_inventory	Checks contents of player or entity inventories	- Supports various inventory types (chests, furnaces, etc.) - Returns Inventory object with count methods - Can query specific items
insert_item	Places items from player inventory into entities	- Works with machines, chests, belts - Validates item compatibility - Returns updated entity
extract_item	Removes items from entity inventories	- Supports all inventory types - Auto-transfers to player inventory - Returns quantity extracted
place_entity	Places entities in the world	- Handles direction and positioning - Validates placement requirements - Returns placed Entity object
place_entity_next_to	Places entities relative to others	- Automatic spacing/alignment - Handles entity dimensions - Supports all entity types
pickup_entity	Removes entities from the world	- Returns items to inventory - Handles entity groups - Supports all placeable items
rotate_entity	Changes entity orientation	- Affects entity behavior (e.g., inserter direction) - Validates rotation rules - Returns updated entity
get_entity	Retrieves entity objects at positions	- Updates stale references - Returns typed Entity objects - Handles all entity types
get_entities	Finds multiple entities in an area	- Supports filtering by type - Returns List[Entity] - Groups connected entities
nearest	Locates closest resources/entities	- Finds ores, water, trees - Returns Position object - 500 tile search radius
get_resource_patch	Analyzes resource deposits	- Returns size and boundaries - Supports all resource types - Includes total resource amount
harvest_resource	Gathers resources from the world	- Supports ores, trees, rocks - Auto-collects to inventory - Returns amount harvested
connect_entities	Creates connections between entities	- Handles belts, pipes, power - Automatic pathfinding - Returns connection group
get_connection_amount	Calculates required connection items	- Pre-planning tool - Works with all connection types - Returns item count needed
set_entity_recipe	Configures machine crafting recipes	- Works with assemblers/chemical plants - Validates recipe requirements - Returns updated entity
get_prototype_recipe	Retrieves crafting requirements	- Shows ingredients/products - Includes crafting time - Returns Recipe object
craft_item	Creates items from components	- Handles recursive crafting - Validates technology requirements - Returns crafted amount
set_research	Initiates technology research	- Validates prerequisites - Returns required ingredients - Handles research queue
get_research_progress	Monitors research status	- Shows remaining requirements - Tracks progress percentage - Returns ingredient list
move_to	Moves player to position	- Pathfinds around obstacles - Can place items while moving - Returns final position
nearest_buildable	Finds valid building locations	- Respects entity dimensions - Handles resource requirements - Returns buildable position
sleep	Pauses execution	- Waits for actions to complete - Adapts to game speed - Maximum 15 second duration
launch_rocket	Controls rocket silo launches	- Validates launch requirements - Handles launch sequence - Returns updated silo state
print	Outputs debug information to stdout	- Supports various object types - Useful for monitoring state - Returns formatted string

Project Structure

Below is an overview of how the project is structured. Some directories also contain more detailed readmes.

factorio-learning-environment/
├── agents/                            # Factorio Learning Environment
│     ├── utils/                          # Some utilities for building an agent
│     ├── agent_abc.py                    # Abstract class to extend
│     └── basic_agent.py                  # Agent implementation we used for our experiments
├── env/                            # Factorio Learning Environment
│     ├── src/                          # Main implementation
│     │     ├── exceptions/                 # Custom exceptions (WIP)
│     │     ├── gym/                        # Gym environment wrapper (deprecated but possibly useful)
│     │     ├── lib/                        # General purpose Lua utilities (e.g serialization etc)
│     │     ├── models/                     # Core objects used during eval
│     │     ├── rcon/                       # RCON wrapper for communicating with the game
│     │     ├── tools/                      # Agent and admin tools
│     │     │    ├── admin/                     # ~17 Tools for managing state, persistence, scoring etc 
│     │     │    └── agent/                     # ~27 Tools that the agent can use
│     │     ├── utils/                      # Python utilities
│     │     ├── entities.py                 # Python object model of the game entities
│     │     ├── game_types.py               # Technologies, Recipes, Resources
│     │     ├── instance.py                 # Environment state manager
│     │     └── namespace.py                # Namespace the agent can read/write variables to. 
│     └── tests/                        # ~350 test cases
├── cluster/                        # Everything needed to launch Factorio servers
│     ├── docker/                       # Docker container definition of the Factorio server
│     │     ├── config/                     # Factorio server configuration files
│     │     └── mods/                       # Mods (deprecated)
│     ├── local/                        # Tools for dynamically creating Docker Compose files for clusters
│     ├── remote/                       # Tools for deploying Factorio clusters onto AWS 
│     └── scenarios/                    # Factorio scenarios for Lab-play and Open-play
│         ├── default_lab_scenario/
│         └── open_world/
├── data/                           # Miscellaneous data
│     ├── blueprints_to_policies/       # Code to scrape Factorio blueprint sites and create Python policies
│     ├── icons/                        # Icons for Factorio entities and items
│     ├── prompts/                      # Prompts (deprecated)
│     ├── recipes/                      # Factorio recipes in JSONL format
│     └── scripts/                      # Misc Lua scripts (deprecated)
├── docs/                           # Website
│     └── assets/                       # Videos / Images
└── eval/
      ├── open/                     # Implementations for running agents in the open game
      │     ├── beam/                   # Implementation for Beam sampling
      │     ├── independent_runs/       # Implementation for independent eval runs
      │     ├── mcts/                   # Implementation for MCTS sampling
      │     └── plots/                  # Run results and plots
      └── tasks                     # Implementations for running agents against lab-play tasks
            ├── task_definitions/       # JSON definition of task
            ├── task_abc.py             # Abstract task definition
            └── throughput_task.py      # A basic task checking for a production throughput quota

Benchmarks

We measured FLE execution performance across different configurations to measure performance. All benchmarks were run on a Macbook Pro M4 128GB, with 100 iterations per operation on a subset of the existing tools.

Direct API Calls (Factorio Client)

Executing tools against the Factorio server, while a Factorio game client is connected.

Operation	Operations/Min	Operations/Sec
place_entity_next_to	2,578.20	42.97
place_entity	12,057.63	200.96
move_to	8,649.89	144.16
harvest_resource	16,599.44	276.66
craft_item	16,875.14	281.25
connect_entities	1,664.70	27.74
rotate_entity	12,281.31	204.69
insert_item	13,044.42	217.41
extract_item	17,167.43	286.12
inspect_inventory	17,036.32	283.94
get_resource_patch	7,004.49	116.74
Total	7,513.29	125.22

Direct API Calls (Headless)

Executing tools against the Factorio server without a game client.

Operation	Operations/Min	Operations/Sec
place_entity_next_to	4,856.51	80.94
place_entity	22,332.72	372.21
move_to	16,005.59	266.76
harvest_resource	32,727.01	545.45
craft_item	36,223.63	603.73
connect_entities	2,926.01	48.77
rotate_entity	23,467.46	391.12
insert_item	25,154.28	419.24
extract_item	32,997.26	549.95
inspect_inventory	28,401.56	473.36
get_resource_patch	8,736.30	145.61
Total	13,094.98	218.25

Python Interpreter (Factorio Client)

Executing tools as part of a Python policy string, while a Factorio game client is connected.

Operation	Operations/Min	Operations/Sec
place_entity_next_to	4,714.52	78.58
place_entity	4,774.13	79.57
move_to	4,005.77	66.76
harvest_resource	3,594.59	59.91
craft_item	4,985.02	83.08
connect_entities	1,497.11	24.95
rotate_entity	4,914.69	81.91
insert_item	5,046.99	84.12
extract_item	4,743.08	79.05
inspect_inventory	4,838.31	80.64
get_resource_patch	2,593.11	43.22
Total	3,639.10	60.65

Python Interpreter (Headless)

Executing tools as part of a Python policy string, without a game client.

Operation	Operations/Min	Operations/Sec
place_entity_next_to	5,069.60	84.49
place_entity	5,238.61	87.31
move_to	4,979.59	82.99
harvest_resource	3,247.09	54.12
craft_item	5,854.27	97.57
connect_entities	2,150.21	35.84
rotate_entity	5,370.21	89.50
insert_item	5,065.89	84.43
extract_item	5,449.07	90.82
inspect_inventory	5,638.67	93.98
get_resource_patch	2,479.41	41.32
Total	4,103.53	68.39

Key Observations

1. Headless vs Client Performance: The headless server configuration consistently outperforms the client version, with direct API calls showing approximately 74% better throughput (218.25 vs 125.22 ops/sec).

2. Interpreter Overhead: Adding the interpreter layer introduces significant overhead:

   • Headless: Drops from 218.25 to 68.39 ops/sec (~69% reduction)
   • Client: Drops from 125.22 to 60.65 ops/sec (~52% reduction)

3. Operation Variability: Some operations show more significant performance variations:

   • connect_entities is consistently the slowest operation across all configurations (because it relies on pathfinding)
   • craft_item and extract_item tend to be among the fastest operations