Fill

Sharpen your mind with a connect-the-block-style one-line brain training puzzle game.
A simple but addictive one-line puzzle game that’s completely free to play.

Your brain becomes more active the more you play.
During your commute, before you sleep… enjoy downtime with brain training.

The rules are extremely simple.
Just fill in all of the blocks using only one line.

Use hints for puzzles that are too hard to solve.
Hints are also free, of course.

4 levels of difficulty.
A whopping 2,000 puzzles.
Don’t get too cozy—the puzzles get harder as you go along.

One-line puzzles are mathematical problems with origins in the early 18th century. First posed in Königsberg, the original puzzle revolved around the town’s Pregel River.
Mathematical thinking is said to increase work efficiency and prevent aging.
Whether math is your bane or your forte, be sure to give this game a try.
You’re sure to get hooked on these puzzles!