Knotilus

Knotilus is a browser puzzle built on the Fibonacci idea. In a Fibonacci-like sequence each number from the third on is the sum of the two before it, as in 1, 5, 6, 11. Each day the game deals out a row of numbers, and several such four-number sequences can be made from them. The help page says there are 4 to 10 on any day.

You build a sequence by tapping four numbers in increasing order, and the game takes it as soon as the fourth fits. Only one set of three sequences solves the day. One number, the knot, sits in all three, and each of the other numbers is used exactly once. On 29 October 2026 the level 10 puzzle had four possible sequences, and three of them tied together at the number 1.

There are three levels, set by how many numbers are in play: 10, 11 or 12. Each level has its own puzzle for the date. Easy mode adds visual cues while you solve, and Hard mode takes them away. Three lock icons each give away one solution sequence if you are stuck. A timer runs until you pick the right three, and then any sequences you missed are revealed.

The game keeps stats and streaks in your browser and compares your time with benchmarks from other players. It also runs a weekly leaderboard and a seasonal team competition called the Golden Ratio League. Every day since October 2024 can be replayed from the archive. The sums are small, so the challenge is in the elimination. It suits players who like a short logic puzzle with numbers more than a race of mental arithmetic.