SUPPLY AND DEMAND
Prices set by simulated market forces — goods cheap where produced and dear where scarce, gluts crashing values, shortages spiking them — rather than fixed vendor tables.
- SOLO-DEV COST HIGH
- TIMING REAL-TIME / TURN
- COMMON IN SIM · STRATEGY · MMO · OPEN-WORLD
Mount & Blade's regional prices built the medium's most approachable version (buy grain at the farm, sell at the siege — the caravan game), X4 and EVE Online run production-consumption simulations deep enough that player actions move real curves, Offworld Trading Company makes the market itself the battlefield (every purchase raises the price your rival pays next), Anno chains island economies through scarcity, and Recettear charmingly localizes it to one shop's haggling. Designers simulate supply and demand because it makes economies playable rather than decorative: fixed prices reduce trade to a faucet (find the best margin once, repeat forever), but moving prices make commerce a reading skill — profit lives in information (where is scarce? what will war make dear?), player success self-corrects (your own selling saturates the market, forcing route rotation), and the economy becomes a system that answers back, pricing in what everyone including you just did. Simulated markets also transmit the world's events as economic weather (the war zone's iron prices tell the story before the newsfeed does) and enable manipulation gameplay for advanced players: cornering, dumping, and blockading become strategies the moment prices respond to quantity. The fidelity spectrum matters: elasticity formulas faking responsiveness are cheap and sufficient for trading games, while true production-consumption simulation (goods actually made, moved, consumed) supports emergent depth at real engineering cost. Key decisions: price responsiveness and recovery speed (instant response invites ping-pong exploits; slow recovery makes saturation strategic), information access (visible remote prices make trading logistics; hidden ones make it exploration), and whether NPCs trade on the same market — an economy only players touch is a vending machine with a curve. Pitfall: simulation without stabilizers — genuine market dynamics happily spiral (feedback loops crashing entire goods permanently), and the realistic-but-degenerate economy that ruins a save is the genre's classic postmortem; simulated markets need dampening, floors, and sinks, because the design goal is an economy that feels alive, not one that dies authentically.