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We investigate the complexity of the platform video game Celeste. We prove that navigating Celeste is PSPACE-hard in five different ways, corresponding to different subsets of the game mechanics. In particular, we prove the game PSPACE-hard…

Computational Complexity · Computer Science 2022-11-23 Lily Chung , Erik D. Demaine

We study the computational complexity of distance games, a class of combinatorial games played on graphs. A move consists of colouring an uncoloured vertex subject to it not being at certain distances determined by two sets, D and S. D is…

Computational Complexity · Computer Science 2019-02-12 Kyle Burke , Silvia Heubach , Melissa Huggan , Svenja Huntemann

We prove PSPACE-completeness of all but one problem in a large space of pulling-block problems where the goal is for the agent to reach a target destination. The problems are parameterized by whether pulling is optional, the number of…

Computational Complexity · Computer Science 2023-11-16 Hayashi Ani , Sualeh Asif , Erik D. Demaine , Jenny Diomidova , Dylan Hendrickson , Jayson Lynch , Sarah Scheffler , Adam Suhl

Temporal graphs extend ordinary graphs with discrete time that affects the availability of edges. We consider solving games played on temporal graphs where one player aims to explore the graph, i.e., visit all vertices. The complexity…

Computer Science and Game Theory · Computer Science 2025-06-16 Pete Austin , Nicolas Mazzocchi , Sougata Bose , Patrick Totzke

The main result of this paper is that computing the value of a one-clock priced timed game (OCPTG) is PSPACE-hard. Along the way, we provide a family of OCPTGs that have an exponential number of event points. Both results hold even in very…

Computer Science and Game Theory · Computer Science 2020-03-06 John Fearnley , Rasmus Ibsen-Jensen , Rahul Savani

We are going to show that some variants of a puzzle called Pull in which the boxes have handles (i.e. we can only pull the boxes in certain directions) are NP-hard

Computational Complexity · Computer Science 2018-01-01 Oscar Temprano

We study \emph{partial-information} two-player turn-based games on graphs with omega-regular objectives, when the partial-information player has \emph{limited memory}. Such games are a natural formalization for reactive synthesis when the…

Formal Languages and Automata Theory · Computer Science 2020-02-19 Dhananjay Raju , Rüdiger Ehlers , Ufuk Topcu

Hive is an abstract strategy game played on a table with hexagonal pieces. First published in 2001, it was and continues to be highly popular among both casual and competitive players. In this paper, we show that for a suitably generalized…

Computational Complexity · Computer Science 2026-05-20 Daniël Andel , Benjamin Rin

We present a new game, Dots & Polygons, played on a planar point set. Players take turns connecting two points, and when a player closes a (simple) polygon, the player scores its area. We show that deciding whether the game can be won from…

Computational Geometry · Computer Science 2020-05-27 Kevin Buchin , Mart Hagedoorn , Irina Kostitsyna , Max van Mulken , Jolan Rensen , Leo van Schooten

Temporal graphs are a popular modelling mechanism for dynamic complex systems that extend ordinary graphs with discrete time. Simply put, time progresses one unit per step and the availability of edges can change with time. We consider the…

Logic in Computer Science · Computer Science 2024-01-30 Pete Austin , Sougata Bose , Patrick Totzke

In this paper we study the computational complexity of the game of Scrabble. We prove the PSPACE-completeness of a derandomized model of the game, answering an open question of Erik Demaine and Robert Hearn.

Computational Complexity · Computer Science 2012-01-26 Michael Lampis , Valia Mitsou , Karolina Sołtys

Amazons is a board game which combines elements of Chess and Go. It has become popular in recent years, and has served as a useful platform for both game-theoretic study and AI games research. Buro showed that simple Amazons endgames are…

Computational Complexity · Computer Science 2007-05-23 Robert A. Hearn

We define a new, partizan, loopy combinatorial game, Forced-Capture Hnefatafl, similar to Hnefatafl, except that players are forced to make capturing moves when available. We show that this game is PSPACE-hard using a reduction from…

Computational Complexity · Computer Science 2023-06-21 Kyle Burke , Craig Tennenhouse

We consider the following modification of annihilation game called node blocking. Given a directed graph, each vertex can be occupied by at most one token. There are two types of tokens, each player can move his type of tokens. The players…

Computer Science and Game Theory · Computer Science 2021-03-05 Dariusz Dereniowski

Games on graphs provide a natural and powerful model for reactive systems. In this paper, we consider generalized reachability objectives, defined as conjunctions of reachability objectives. We first prove that deciding the winner in such…

Computational Complexity · Computer Science 2012-02-06 Nathanaël Fijalkow , Florian Horn

We expand the theory of pebbling to graphs with weighted edges. In a weighted pebbling game, one player distributes a set amount of weight on the edges of a graph and his opponent chooses a target vertex and places a configuration of…

Combinatorics · Mathematics 2011-06-09 Stephanie Jones , Joshua D. Laison , Cameron McLeman , Kathryn Nyman

Many problems in compositional synthesis and verification of multi-agent systems -- such as rational verification and assume-guarantee verification in probabilistic systems -- reduce to reasoning about two-player multi-objective stochastic…

Computer Science and Game Theory · Computer Science 2026-02-16 Moritz Graf , Anthony Lin , Rupak Majumdar

Poset games are a class of combinatorial game that remain unsolved. Soltys and Wilson proved that computing wining strategies is in \textbf{PSPACE} and aside from special cases such as Nim and N-Free games, \textbf{P} time algorithms for…

Combinatorics · Mathematics 2021-01-26 Alexander Clow , Stephen Finbow

We study the complexity of solving two-player infinite duration games played on a fixed finite graph, where the control of a node is not predetermined but rather assigned randomly. In classic random-turn games, control of each node is…

Computer Science and Game Theory · Computer Science 2026-01-13 Sarvin Bahmani , Rasmus Ibsen-Jensen , Soumyajit Paul , Sven Schewe , Friedrich Slivovsky , Qiyi Tang , Dominik Wojtczak , Shufang Zhu

We analyze the computational complexity of several new variants of edge-matching puzzles. First we analyze inequality (instead of equality) constraints between adjacent tiles, proving the problem NP-complete for strict inequalities but…