Draw What Happened Next in Extraplot
Extraplot shows you the beginning of a real historical chart. Draw your guess for the missing stretch, then reveal the actual data and see how closely your line matches.
Extraplot is a free daily chart-guessing game. Each round shows the first part of a real historical chart — from stocks, climate, population, earth science, or energy — and you draw the line for what happens next. When you reveal the answer, Extraplot scores your guess against the actual data so you can see exactly where your prediction ran high or low.
BUILD YOUR SET
Choose a category
Pick a topic and draw what happened next on up to five random charts.
103 charts ready
Play history
0 / 103 playedShows the latest score and best score for each chart, saved in this browser.
Reveal your first chart to see its score here.
WHY EXTRAPLOT
A calm way to test your sense of history
No trivia facts to memorise — just read the line in front of you and trust your intuition.
Real historical data
Every chart is built from an actual series — stocks, climate, population, earth science, and energy.
Draw, don’t describe
Sketch the line itself. It’s faster, more intuitive, and oddly hard to put down.
See exactly where you were off
Reveal the real trend and your score, then read the story the data was telling.
Average miss 0.42
HOW TO PLAY
How to Play Extraplot
Each chart has a visible section and a hidden section. Use the visible data, dates, and scale to decide how to continue the line.
Choose a Category
Pick one topic or select All categories to draw from the full question bank. Each set contains up to five randomly selected charts.
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.
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.
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.
Browsing, drawing, and revealing every chart are free — no login or account needed. Only the final See results summary is a one-time $7.9 payment through Stripe’s secure hosted checkout.
Read the Clues in Every Extraplot Chart
Start with what the chart tells you: its topic, dates, units, and visible pattern. Use those clues to decide how the missing line might continue.
Check the Vertical Scale
Read the axis labels before judging the steepness of a line. A small change in value can look large when the chart covers a narrow range.
Look at the Full Visible Pattern
Check whether the visible line rises steadily, repeats a seasonal pattern, or swings between peaks and dips. Use that pattern to decide where your guess should change direction.
Refine Your Guess
Use Undo to remove your last stroke or Clear to start the chart over. You can revise any part of the shaded section before selecting Reveal.
AFTER YOU REVEAL
See How Your Extraplot Guess Compares
Reveal the actual trend alongside your guess, see where the lines match or diverge, and check how close you came with your score and average miss.
- Your guess appears in amber and the revealed data appears in violet. The space between the lines shows where your prediction was too high or too low.
- Each chart is worth up to 1,000 points. The result also shows the average distance between your guess and the actual values across the hidden section.
- The source link appears when you reveal a chart. Open it to find the original dataset and check what the series measures.
- The set summary lists every chart and your total score. Open an individual result to review your prediction and the actual line.
Explore Five Categories in Extraplot
Discover more than 100 real charts across stocks, climate, population, earth science, and technology & energy. Focus on a favorite topic or mix categories to try a different kind of trend each round.
Compare Short and Long Time Spans
Try Stocks for daily closing prices, then switch to Population to read changes in fertility, life expectancy, or the share of people living in cities over longer periods.
Look for Different Patterns
In Climate, compare seasonal patterns in atmospheric carbon dioxide with shifts in sea ice. In Earth Science, try charts of earthquake counts, volcanic eruptions, and tsunamis.
Explore Technology Adoption and Energy
Choose Technology & Energy to compare how internet use, mobile subscriptions, and electricity generation from sources such as wind and solar changed over time.
Track Which Charts You Have Played
Open Play history to see your latest score, best score, and play count for each completed chart. Turn on Exclude played charts when you want a set of questions you have yet to reveal.
Go deeper with Extraplot
Full rules, every real chart, and guides to reading data.
Extraplot FAQ
Answers about drawing, scoring, question sets, and saved results.
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.