How to Play Playplain
Seven rounds, two ways to guess, and a plane that climbs with your accuracy. Here is what to expect before you take off.
Two kinds of estimation round
In a Name it round, you see a target and type a country or planet whose value is close. The input suggests names from that round’s collection without showing their values. Choose one of those names; we cannot score an object outside the collection. Common aliases such as USA and UK are accepted. A single small typo is also accepted when it identifies exactly one name; ambiguous guesses need a selection from the list.
Name it: planet size
Imagine a target diameter of 13,000 km. Earth is 12,756 km across at the equator, so it is a close choice. The reveal shows the closest planet in our list and the NASA reference behind it.
In an Estimate it round, a named object is given and you type a number. Read the units carefully: a planet’s orbital period is in Earth days, while its diameter is in kilometers. Country questions include the year of the dataset.
Estimate it: a year on Mars
Mars takes about 687 Earth days to orbit the Sun. A guess of 700 is 13 days away, or approximately 1.9% of the reference value. That is a close estimate even though it is not exact.
How accuracy becomes altitude
For a number round, error is the absolute distance between your guess and the answer, divided by the answer. Accuracy is one minus that error, with a floor of zero. An exact guess earns 1,000 meters before the clock deduction; a guess 10% away earns 900 meters.
For a naming round, the closest available answer earns full accuracy even if the target sits between two values. Other answers lose accuracy for the extra distance beyond that best available answer. This keeps a generated target fair: you do not need an object with a value that does not exist in the list.
| Result | Accuracy | Before the clock |
|---|---|---|
| Pinpoint | 99–100% | 990–1,000 m |
| Close | 90–under 99% | 900–989 m |
| On course | 70–under 90% | 700–899 m |
| A little turbulence | Above 0–under 70% | Up to 699 m |
| Missed or too far away | 0% | 0 m |
The clock and final round
Timed rounds last 30 seconds. Time starts when the question is ready after you press Start or Next round. Each elapsed second subtracts four meters from that round’s climb. A skipped or expired round adds no altitude; a poor guess never removes altitude you already earned.
The seventh round doubles the accuracy-based climb before subtracting the time cost. The theoretical maximum for seven rounds is 8,000 meters. In unlimited practice, relaxed flight turns off both timeout and time deduction. Its shared results are marked Relaxed, so they are easy to distinguish from timed scores.
Daily progress and resets
The daily flight changes at 00:00 UTC. Everyone gets the same versioned seven-round selection for that date. Progress and sound preferences are stored in this browser. Refreshing resumes the same challenge; an active timed question keeps its original deadline.
Finishing a daily flight adds that date to your local streak. Clearing browser storage, using another browser or private browsing may remove that history. There are no accounts or cross-device score synchronization. Unlimited flights are fresh practice runs and do not overwrite the daily challenge.
Answers, sources and corrections
Use digits for number questions; commas and decimal points are accepted. Do not add unit symbols or words such as “million”: enter the full number in the displayed unit. For name questions, use the suggestions to check which answers are available.
Every reveal links to its factual source. Read the data notes for years, units and attribution. If a value differs from another reference, compare the data year, units and measurement method first. These are our own puzzles; see About for the relationship to the original Plain game.