Tera.
Tera is the map view: a city from above, rendered in three.js, open at tera.lumbridgecorp.com with no account and no login. The map is a static bundle, so opening the page is the whole of getting in. Spaces is the other half, the interiors you go inside; this page is the outside.
A city is data, not code
A city pack is one file under src/cities/ exporting a City: coastlines, inland water, parks, named hills, districts with a street bearing each, landmarks, bridges, roads and camera chapters, and no code at all. Two ship. San Francisco runs from the Golden Gate to San Jose at about 94 m per scene unit — 83 named hills, a 0.53M-point heightfield, ~3.8 s to build, ~83,000 instanced buildings, 12 camera chapters. Southern California covers LA, Orange County and Riverside at 391 m per unit — 66 hills, 0.13M points, ~2.3 s, ~55,000 instances, 8 chapters.
Tallest, plus 35% of the rest
The ground is a heightfield built from the pack's named hills, each a radial peak with an elevation and a radius, roughened by four octaves of value noise. Overlapping hills combine as the tallest plus 35% of the rest: a straight sum puts Twin Peaks and Mount Sutro, 1.2 km apart at 281 m and 275 m, at a fictional 500 m, and a plain maximum leaves a notch between them. Resolution is per-city — a pack declares focusRegions and a coarseFactor, and refinement is per axis rather than per rectangle, so two regions at opposite corners refine nearly everything between them.
Hand-traced, and never OpenStreetMap
Every coordinate in src/cities/ is traced by hand. OpenStreetMap geometry would make the packs ODbL, and containment does not discharge that: serving a snapshot of those coordinates is Public Use of a Derivative Database, so attribution and share-alike attach wherever the rows are stored. The sanctioned geocoder is the US Census Geocoder, a US-government work in the public domain. Google, Mapbox and HERE do not solve it either — they restrict redistributing the coordinates they return. Every synced row carries a provenance field and the publication gate refuses any row not on the allowlist.
Aircraft, and no FlightRadar24
The engine takes a FlightSource and the repository ships only sources it can give away: a simulator flying real approach and departure corridors, and clients for open community ADS-B — adsb.lol, or a local dump1090 receiver. There is no FlightRadar24 client, because their terms forbid scraping and forbid redistributing their data, so one cannot live in an Apache-2.0 repository at all.
Not built: company data — the marker sync path and its provenance allowlist are specified and nothing is wired to them. New York is not written. Southern California's two harbour bridges size their members in scene-unit constants tuned at San Francisco's 94 m per unit, so at 391 they render about four times too heavy.