How to Play Extraplot
Extraplot is a free chart game built on real historical data. You see the beginning of a real chart and draw what you think happens next. This guide covers the rules, the scoring, and a few tips to improve your guess.
The four steps
1. Choose a category
Pick a topic — Stocks, Climate, Population, Earth Science, or Technology & Energy — or select All categories to draw from the full question bank. Each set contains up to five randomly selected charts.
2. Draw the missing line
Start at the dotted cutoff and draw across the shaded area to the right edge. Draw over any section to revise your guess before submitting it.
3. Reveal the actual data
Select Reveal when your line is complete. Compare your guess with the actual trend, see your score, and open the source link to learn where the data came from.
4. Review the set
Finish the remaining charts, then select See results to view your total and full breakdown. Open an individual result to compare the lines again, or start another set.
How scoring works
Extraplot measures the average distance between your drawn line and the actual values across the hidden section. It compares that average with the chart’s vertical range and converts the result into a score from 0 to 1,000 — a closer match earns more points. The result screen also shows your average miss, the gap between your guess and the real line at each hidden point.
Tips for a better guess
- •Read the vertical scale first. A small change in value can look large when the chart covers a narrow range.
- •Look at the full visible pattern: does the line rise steadily, repeat a seasonal wave, or swing between peaks and dips?
- •Use Undo to remove your last stroke or Clear to start the chart over. You can revise any part of the shaded section before revealing.
- •Reveal is free. Open the Source link on every chart to see the original dataset and what the series measures.
Frequently asked questions
What is Extraplot?
Extraplot is a browser game where you guess the hidden part of a chart by drawing a line. The charts use real historical observations. When you finish your line, reveal the data to see what happened and how closely your guess matched it.
How is my Extraplot score calculated?
Extraplot averages the absolute difference between your line and the actual values at all hidden points. It compares that average with the chart’s vertical range to calculate a score from 0 to 1,000. A closer match earns more points.
Can I draw with a keyboard?
Yes. Press Tab to focus the chart. Use Left and Right to move between points and Up and Down to adjust the value. Hold Shift to make larger adjustments.
What kinds of data can I play?
Extraplot offers Stocks, Climate, Population, Earth Science, and Technology & Energy. Choose a category for a set from that topic, or select All categories to draw from the entire question bank.
How do I skip charts I have already played?
Turn on Exclude played charts before starting a set. The picker filters out charts you have already revealed in that browser, including charts that earned zero points.
What happens if fewer than five charts are available?
Extraplot lets you start a shorter set if one to four charts match your selection. If none are available, choose another category or turn off Exclude played charts to allow repeats.
Where can I find the source of a chart?
Reveal the chart to see its Source link — revealing is free. You can open the original data provider’s page to look up the series and its measurement details.
Do I need an account to play Extraplot?
No account or login is needed. Browsing categories, drawing your guess, and revealing each chart’s result are all free. Only the final See results screen — your total score and full set breakdown — requires a one-time $7.9 payment through Stripe’s secure hosted checkout. Your purchase is saved in this browser.
Will my scores still be there after I refresh?
Yes, when browser storage is available. Extraplot records each score when you reveal the chart and shows your latest and best scores in Play history. Refreshing returns you to the category picker and clears unfinished drawings.