Standard and Hard
Two boards a day, the same two for everyone, and a leaderboard that closes at midnight. Miss a day and a freeze can cover it — you earn one for every seven days in a row, and hold at most two.
One board a day
Four colours are always enough.
Colour every node so that no two joined by a line ever match. It is never impossible, and it is rarely obvious. A new board arrives each morning — the same one for everyone.
Free to play · iPhone and Android
The rule
One rule, and it never changes.
Two nodes joined by a line cannot share a colour. Every board can be solved with four — because every board is planar, and a planar map has never needed a fifth. That is a theorem, not a promise we are making.
▲ Amber
● Sky
■ Jade
◆ Orchid
Every colour carries a shape, so the board stays solvable without relying on colour at all.
Ways to play
Four ways in, one rule.
Practice
Unlimited boards, untimed and unscored. Depth comes from density and structure, not from a bigger palette — every tier is still four colours.
SeedTheoremProofAxiom
Duels
One duel at a time, the same puzzle for both of you, twenty-four hours to answer. Win, lose or draw goes into a history you can both read.
The archive
Past boards, playable whenever. Solving one leaves your streak exactly as it was — the archive is for catching up, not for repairing a run.
Getting faster
Five things that shave seconds.
Pick the colour, then tap
Tapping a node without choosing first cycles through all four. Select from the palette and each tap is one move instead of up to four. Long-press clears a node outright.
Start where it is tightest
Find the node touching the most others and colour it first. Every neighbour it constrains is a decision you no longer have to make later.
Take the forced moves first
A node whose neighbours already show three different colours has exactly one colour left. There is nothing to think about — place it, and watch what it forces next.
Count the ring before you commit
A ring with an even number of nodes takes two colours, alternating. An odd ring always needs three, no matter how you arrange it. Counting first saves undoing later.
A clash is information
When two joined nodes match, the red ring is on the one you just placed. It is telling you which decision to take back — usually the one before it, not the one you are looking at.
The details
The things nobody tells you.
- Friend code
- Six characters. Share it, or scan someone else's.
- Friends
- Up to 100. Ten friend requests a day.
- Nudges
- Ten a day, and one per friend per day. A nudge only sends if that friend still has a board open.
- Duels
- One open duel at a time. Same puzzle both sides, 24 hours to play it.
- Your name
- Up to 14 characters, starting with a letter. You can also nickname a friend privately — they never see it.
- Streak freezes
- Up to two held at once. One is earned for every seven days in a row, and it covers a missed day automatically.
- Archive boards
- Playable any time and never counted toward a streak, in either direction.
- Your avatar
- A symbol, a board theme and a wallpaper. It saves on the device at once and reaches other players the next time you save while online.
- Symbols
- Shapes, letters, suits, cosmic or botanical — a shape inside every colour. Turn them off in settings for colour only.
- Reporting
- From the leaderboard you can report a name or a time. The board and rank go with the report; the person is told nothing. From a friend you can block and report, or report the name only and stay friends.
What we left out
Nothing here is watching you.
No advertising and no third-party analytics — neither is built into the app, so there is nothing to opt out of. There is no email address and no password either: your device gets an anonymous ID and a friend code, and that is the whole account. Crash reports go to our own server in Frankfurt rather than to a tracking vendor.
A note from me
There is a theorem that went unproved for 124 years: four colours are enough for any map you can draw flat. However many countries, however many borders — four will always do.
I read about it a few years ago and could not stop turning it over. One rule. No instructions. A board that is never impossible and rarely obvious. It was asking to be a game.
So I made one. Evenings and weekends, by myself. Every board, every colour, every line of the server it talks to.
And I kept it small on purpose. No advertising, because I did not want to build the part that puts it there. No account, because handing over an email to play a puzzle is an indignity. No analytics, because I would rather not watch you.
Play it, and if something is wrong, write to me. It is one inbox, and I read all of it.
FILL: your name — this is the one place on the site where it is yours to sign
Today's board
It is already waiting.
Free to play · No ads · No sign-up