AI disclosure
Last updated 9 September 2026
filo was built with the help of AI, specifically Claude Code, Anthropic's AI coding assistant.
The website
Claude Code helped write the majority of the code behind this site — the board, the interface, and the plumbing underneath it.
The puzzle generation algorithms
Claude also worked alongside a human on the harder part: devising and implementing the algorithms that generate filo's puzzles, checks them for solvability and uniqueness, and grades them for difficulty.
Great care has been taken to make the solver employ various strategies that humans use to solve Fillomino puzzles, and rank them according to 'human' effort and difficulty, so that the puzzles are fair and enjoyable for human players. These algorithms and implementations are original and purpose-built over many rounds of design, testing, and evaluation.