Flag Tone is a free, browser-based world flag color guessing game where players reconstruct missing flag colors using HSL sliders and receive perceptual accuracy scores via Delta E.
What is Flag Tone?
Flag Tone is an independent browser-based game that turns flag recognition into a color memory challenge. Players are shown a world flag with one color region hidden; they must reconstruct that color using hue, saturation, and lightness sliders. The game compares the guessed color to the original using Delta E, a perceptual color-difference metric, and outputs a numerical score. It runs entirely client-side in the browser with no account required.
Key Features
- HSL Color Sliders — Adjust hue, saturation, and lightness intuitively; the flag preview updates live as sliders move.
- Delta E Scoring — Each guess is scored with Delta E, a perceptual color-difference formula; lower scores mean closer visual matches.
- 200+ World Flags — Draws from a library of over 200 country and territory flags, viewable in the Flag Library.
- Real-time Preview — The missing flag section updates in real time as you fine-tune your HSL values.
- Shareable Result Cards — After a five-round run, you can save and share a result card to compare scores.
- No Sign-Up Required — The game is pure client-side; just open the play page and start.
Who is it for?
- Geography enthusiasts — Test how well you remember the exact colors of national flags from around the world.
- Designers and artists — Train your color perception and ability to match hues precisely using HSL controls.
- Students and teachers — Use as a fun educational tool to learn flag colors while developing color memory skills.
- Casual players — Enjoy quick, replayable five-round sessions that are easy to start and hard to master.
What can you do with Flag Tone?
- Memorize flag colors: Play through multiple runs to reinforce memory of flag color schemes from 200+ countries.
- Challenge friends: Share your Delta E score card on social media to see who can achieve the lowest score.
- Practice color matching: Use the HSL sliders to improve your ability to visually identify and replicate colors without referencing color codes.
How does Flag Tone work?
- Study the target: Look at the highlighted area of the flag and decide what the missing color should be.
- Adjust the sliders: Move the hue, saturation, and lightness sliders until the preview matches your mental image.
- Submit and score: Click submit to have your guess compared against the original flag color using Delta E; the lower your score, the closer the match.
Frequently Asked Questions
What is Flag Tone?
Flag Tone is a free, browser-based color guessing game that challenges you to reconstruct hidden color regions from world flags using HSL sliders and Delta E scoring.
How do you play?
Each round shows a flag with one area missing its color. You adjust hue, saturation, and lightness sliders to recreate that color, then submit to see how close you were with a Delta E score.
What is Delta E?
Delta E is a perceptual color-difference metric that quantifies how distinct two colors appear to the human eye. In Flag Tone, a lower Delta E means your guessed color more closely matches the original flag color.
Is Flag Tone free?
Yes, Flag Tone is completely free to play. No account or payment is required; it runs entirely in your browser.
What is a good score in Flag Tone?
Scores range from 0 (perfect match) upward. A Delta E under 5 is generally considered an excellent match, while under 2 is nearly indistinguishable.









