Fill One Line puzzles are mathematical problems with origins in the early 18th century. A simple but addictive one line puzzle game that’s completely free to play. --The rules are extremely simple. Just fill in all of the blocks using only one line. --Your brain becomes more active the more you play. During your commute, before you sleep… enjoy downtime with brain training. --Use hints for puzzles that are too hard to solve. Hints are also free, of course. --5 levels of difficulty. A whopping 2,000 puzzles. Don’t get too cozy—the puzzles get harder as you go along. 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!