Daniele Muscillo | Searcharxiv

arXiv2026

One Hex reduction to rule them all: Quoridor, Maze Attack, Pinko Pallino and Blockade are PSPACE-complete

Quoridor is a popular award-winning board game whose computational complexity, listed among the open problems of the Demaine-Hearn survey, remained open for nearly two decades. It was settled only recently, via a reduction from the formula game $G_{pos}$ tailored to Quoridor. We give a shorter and more general proof: a single reduction from Reisch's planar graph-Hex, in which wall placement encodes the path-connection structure of Hex. The same construction settles three closely related games -- Maze Attack and Pinko Pallino with no change, and Blockade with only minor adaptations -- showing that all four are PSPACE-complete, the latter three for the first time. More generally, our reduction shows that any race-and-wall game is PSPACE-complete.

cs.CC↗

arXiv2025

Man, these New York Times games are hard! A computational perspective

The New York Times (NYT) games have found widespread popularity in recent years and reportedly account for an increasing fraction of the newspaper's readership. In this paper, we bring the computational lens to the study of New York Times games and consider four of them not previously studied: Letter Boxed, Pips, Strands and Tiles. We show that these games can be just as hard as they are fun. In particular, we characterize the hardness of several variants of computational problems related to these popular puzzle games. For Letter Boxed, we show that deciding whether an instance is solvable is in general NP-Complete, while in some parameter settings it can be done in polynomial time. Similarly, for Pips we prove that deciding whether a puzzle has a solution is NP-Complete even in some restricted classes of instances. We then show that one natural computational problem arising from Strands is NP-Complete in most parameter settings. Finally, we demonstrate that deciding whether a Tiles puzzle is solvable with a single, uninterrupted combo requires polynomial time.

cs.CC↗