Common Ground
Run a city. Choose how it pays for itself. Watch the economics play out.
Every mechanic in this game comes from peer-reviewed economics — spatial equilibrium, agglomeration, and deadweight loss. Change how your city raises revenue and see rents, wages, buildings and speculation respond.
Take office
Five cities, five fights. Win each act to unlock the next — or practice freely in the sandbox.
Free play
Sandbox
Any map, no goals, no term limits. Just you, a city, and the land question.
The science under the hood
This is a simplified model, but not a made-up one. Each mechanic is calibrated to empirical findings from urban and public economics.
Cities are bid-rent markets
Where homes rise, how tall they get and what land costs all emerge from competition for location. The game follows the Alonso–Muth–Mills model of spatial equilibrium, whose predictions match the internal structure of real cities1.
Bigger cities are more productive
Doubling a city’s size raises everyone’s productivity by a few percent — the agglomeration effect. The game uses the elasticity range found in meta-analyses of hundreds of estimates2.
Land rent can fund the city
At a city’s optimal size, the land rent its community creates exactly equals what worthwhile public goods cost — so land rent alone can fund the city. Proven by Arnott and Stiglitz3, and visible on the game’s gauge.
Taxes on work destroy wealth
Income and sales taxes make some work and trade not worth doing — value that simply vanishes, called deadweight loss. The game computes it with the standard formula and the elasticity from the public-economics literature4.
Land taxes don’t distort
Taxing buildings makes builders build less; taxing land changes nothing about what’s worth building, because land can’t move or shrink. When Pittsburgh taxed land more than buildings, construction measurably rose5.
Land taxes fall on landowners
A tax on land rent can’t be passed on to tenants — it gets capitalized into a lower land price instead. Watch the game’s land price fall as capture rises, exactly as the theory of tax incidence6 predicts.
Common Ground is a teaching model, not a forecast. It compresses a real economy into one stylized city — but the mechanisms it runs on, and the direction of every effect you’ll see, come from published research.