ForecastBench-Sim

A multi-simulation forecasting benchmark that can host an arbitrary number of simulation "worlds." A world runs a simulation, and models read a world-state report and forecast future outcomes. The domain-agnostic machinery (question schema, resolver, generator, scoring, eval harness) lives in fbsim-core; each world is a plugin.

Two worlds ship today:

• FreeCiv (worlds/freeciv/) — strategy-game world on the CivRealm engine.
• Starsim (worlds/pandemic/) — SIR epidemic world with conditional vaccine forecasting.

Adding a third is the Adding a world flow below.

packages/fbsim-core/      # schema, resolver, registry, generator machinery,
                          # metrics, eval (models/sampling/difficulty)
worlds/freeciv/           # FreeCiv strategy-game world (CivRealm engine + benchmark)
worlds/pandemic/          # Starsim SIR epidemic world (conditional vaccine forecasting)

It's a uv workspace. Install with:

uv sync --all-packages

Adding a world

A world provides these to fbsim-core (see worlds/pandemic/ for a compact example):

1. Serializer → game_data in the canonical turn-major layout time_series[metric][turn][entity_id] = value (see fbsim_core.questions.timeseries). Core never infers the layout — the world emits it.
2. Template registry — build a fbsim_core.questions.registry.TemplateRegistry from the world's QuestionTemplates and pass it to QuestionResolver(registry). (worlds/pandemic/pandemic_world/templates.py)
3. Report renderer — a function producing the model-facing world-state text for a snapshot. (pandemic_world/report.py)
4. Eval driver / adapter — turn questions + report into prompts, query models (fbsim_core.evaluation.models), score with fbsim_core.metrics. (pandemic_world/scale_eval.py)
5. (Optional) conditional executor — how an intervention is applied. FreeCiv forks a savegame; pandemic re-runs the sim with a vaccine. Core keeps the generic control-vs-intervention structure; the executor is world-specific.

Verify

# core (domain-agnostic) tests
cd packages/fbsim-core && uv run --project .. python -m pytest tests

# FreeCiv world: generate + resolve questions from a recorded game
uv run python worlds/freeciv/scripts/generate_questions.py \
    data/games/seed1619_data.json --snapshot-turn 60 --summary

# Pandemic world: scaled conditional/unconditional benchmark + chart (cached)
uv run python -m pandemic_world.scale_eval --eval

Both worlds resolve through the same core resolver and registry — that's the point.