Data sources & game rules
An independently built estimation game inspired by Plain. Our factual data comes from the sources below. Each published day uses a frozen snapshot. Values may contain errors, and different definitions can produce different answers.
Names and aliases are curated for this game. Explanations and flight artwork are made for this site. Some names are available in English only.
Mountain heights
Summit elevation above sea level; 100 prominent peaks, table values.
Entries: 100 · Import checked: 2026-10-20
CC BY-SA 4.0 — Wikipedia contributors; linked revision
Original source & version ↗Island areas
Individual islands, not archipelagos or continents; tabulated main-island area.
Entries: 80 · Import checked: 2026-10-20
CC BY-SA 4.0 — Wikipedia contributors; linked revision
Original source & version ↗River-system lengths
Main listed river-system length, including named tributaries. Estimates vary by source.
Entries: 80 · Import checked: 2026-10-20
CC BY-SA 4.0 — Wikipedia contributors; linked revision
Original source & version ↗Country & economy areas
World Bank 2023 surface area, including inland water; economies as listed by the source.
Entries: 79 · Import checked: 2026-10-20
CC BY 4.0 — World Bank WDI, AG.SRF.TOTL.K2 (2023)
Original source & version ↗Atomic numbers
First 100 elements in PubChem. Atomic number is the number of protons.
Entries: 100 · Import checked: 2026-10-20
PubChem / NCBI — factual periodic-table data; original display text and explanations
Original source & version ↗Rules & precision
Rules: plain-independent-v1. Ratio distance d = |ln(answer/target)|. Base points = round(100 × exp(−3.3d)). Tiers use logarithmic boundaries at ratios 1.01, 1.10, 1.35 and 2, inclusive. Dialed adds 25 points. The golden round doubles both base points and the bonus.
Each point climbs 10 m. After 3 free seconds, time costs 4 m/s, up to 108 m. Round altitude = max(0, starting altitude + climb − descent). The server judges the time of receipt; at 30 seconds the round expires. Display values may be rounded; scoring uses full precision. Exact boundaries, puzzle selection and altitude flooring are our own rules.
Country areas follow the World Bank’s economy definitions. The anomalous Canada 2023 area record is excluded pending verification. River lengths follow the main tabulated river-system estimates and do not resolve competing measurements.
Attribution & fonts
Wikipedia-derived categories are provided under CC BY-SA 4.0, credited to the Wikipedia contributors at each linked revision, with selection, restructuring and translated names. World Bank data is credited under CC BY 4.0.
CC BY-SA 4.0 · CC BY 4.0 · PubChem
Barlow Condensed / Atkinson Hyperlegible — SIL Open Font License. Barlow license · Atkinson license