"Difficulty is structural" — a study that exactly decomposes the difficulty of arithmetic puzzles (4OPS, arXiv / accepted at AIED 2026, March 2026)

"Simple-Looking, Surprisingly Tough" — Generating Slit Paperfolding Puzzles at FDG 2026

One piece today: "Difficulty-based generation of paperfolding puzzles" by Stiliyan Nanovski, Mrinal Dhume, and Rafael Bidarra (TU Delft, Netherlands), presented at the Procedural Content Generation Workshop co-located with Foundations of Digital Games 2026 (FDG '26), held August 10–13, 2026 in Copenhagen. The paper generalizes an existing square-grid, slit-based paperfolding puzzle into a model supporting arbitrary shapes and slits, and builds a constraint-solving generator that derives folded states for a given paper shape and size. Puzzle difficulty is scored based on the types of folds required, and the generator surfaced new fold types made possible only by the slits. I was unable to load the full PDF due to its file size, so this summary is based on the authors' published abstract.