Playplain Data Sources
A useful guess needs a trustworthy answer. This page explains the facts, units and dates behind our first question collection.
Playplain data sources currently cover 88 factual records across four categories. These records were independently selected from NASA and World Bank references and checked on October 21, 2026. We do not import the original game’s compiled questions or answer lists.
SPACE: PLANETS
8 planets · equatorial diameter · answers in km.
Eight planets. Equatorial diameter, not radius.
NASA / NSSDCA, Dr. David R. Williams. Fact sheet updated March 18, 2025.
Names included in this collection
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
SPACE: ORBITS
8 planets · orbital period · answers in days.
Eight planets. NASA reference values; orbital periods are measured in Earth days.
NASA / NSSDCA, Dr. David R. Williams. Fact sheet updated March 18, 2025.
Names included in this collection
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
OUR WORLD: POPULATION
36 countries · population in 2024 · answers in people.
2024 World Bank data. 36 countries in the answer list. Use the displayed data year, not today’s population.
World Bank, World Development Indicators, 2024. CC BY 4.0. Curated selection; original values retained.
Names included in this collection
Argentina, Australia, Bangladesh, Brazil, Canada, Chile, China, Colombia, Egypt, France, Germany, India, Indonesia, Italy, Japan, Kenya, Mexico, Netherlands, New Zealand, Nigeria, Norway, Pakistan, Peru, Philippines, Poland, Saudi Arabia, South Africa, South Korea, Spain, Sweden, Switzerland, Thailand, Turkey, United Kingdom, United States, Vietnam.
OUR WORLD: GEOGRAPHY
36 countries · surface area in 2023 · answers in km².
2023 World Bank data. 36 countries in the answer list. Surface area includes inland water.
World Bank, World Development Indicators, 2023. CC BY 4.0. Curated selection; original values retained.
Names included in this collection
Argentina, Australia, Bangladesh, Brazil, Canada, Chile, China, Colombia, Egypt, France, Germany, India, Indonesia, Italy, Japan, Kenya, Mexico, Netherlands, New Zealand, Nigeria, Norway, Pakistan, Peru, Philippines, Poland, Saudi Arabia, South Africa, South Korea, Spain, Sweden, Switzerland, Thailand, Turkey, United Kingdom, United States, Vietnam.
How we use the facts
Naming rounds choose a target close to an actual record and ask you to find the nearest available object. Number rounds ask for a record’s value. Targets and wording are our own; the underlying measurements remain attributed to their source. Values are shown with the category’s display precision, and the score uses the stored reference value.
World Bank data is used under CC BY 4.0. We select a subset of countries and present their names in familiar English forms. NASA planetary values are approximate reference measurements. Diameter is equatorial diameter, not radius; orbital periods are in Earth days. Neither source endorses this game.
Stable daily challenges
The first collection is version v1. A daily puzzle is tied to its date and data version. Published selections must not change when the collection grows. A material correction requires a new version and an effective date; old versions are kept so saved daily results remain understandable.
See how we choose the game’s collection, then try the facts in a daily flight or unlimited practice.
Spot a mismatch?
Check the year and units first, then compare the linked source. Different sources can use different reference dates or measurement methods; this game uses the snapshots listed above. The scoring explanation distinguishes distance from the target from the closest answer available in our list.