AoE4 Foundry

AoE4 Foundry lets you test Age of Empires IV openings without loading the game. Set up villager production, resource assignments, buildings, and technologies, then run the build order on an isometric map. You can pause or move through the timeline to check timings and resource use.

It simulates the economy and opening build. Combat, fog of war, and opponents are not included. The same inputs produce the same result, which makes it possible to compare changes to a build order.

Why did I build it?

I play AoE4 and wanted to compare build orders without repeating each opening in the game. For example, does a different villager assignment get me to the Feudal Age sooner? Building a simulator was also a chance to work on something quite different from my usual frontend work.

What it models

The event-driven simulation uses game data for units, buildings, technologies, and costs. It covers villager movement, gather rates and carry capacity, production queues, building placement, and food transitions. The dataset includes 23 civilizations with their landmarks and economic bonuses.

The map uses PixiJS. Alongside it, the analysis view shows resources, villager growth, income per minute, and idle time. Validation points out missing resources, blocked placements, population caps, and missing prerequisites. The bottleneck panel helps identify idle villagers, Town Center downtime, and time spent walking.

Saving builds

You can save a build, copy it to try a variation, or share it with other players. The library also includes public builds. You can use the simulator without an account; signing in syncs saved builds across devices.

Keeping up with patches

Game patches change the numbers the simulation uses. The data:transform and data:validate commands rebuild and check the dataset. The app shows which patch it uses and documents its approximations and missing mechanics.

Technical details

• React + TypeScript frontend, Convex for persistence and sharing saved builds.
• The simulation runs in the browser, separately from React.
• Validation runs in CI: types, tests, data checks, and build must all pass (pnpm verify).

Keeping the simulation separate from React made it easier to test and move into a worker. Checking the game data before running a simulation also helped catch bugs closer to their source.