This special issue of the International Journal of Game Theory was dedicated to papers in the field of Combinatorial Game Theory (CGT). Combinatorial games are traditionally two-player perfect-information games with compact rules, and a rich mathematical structure. As reflected in this issue, activity in CGT accommodates infinite and cyclic games, games with a winning score, or one-player and multi-player games, which freshens up the theory.

In Portugal, under the auspices of Associação Ludus, Carlos Pereira dos Santos has been organizing the Combinatorial Game Theory Colloquia taking place every two years, starting in January 2015, 2017, 2019, and next in 2023. Authors of significant original results related to (or/and presented at) the conference are encouraged to submit them by September 1, 2023 to the International Journal of Game Theory. It is the editorial policy of IJGT that all submissions are thoroughly reviewed and screened for quality, so this is not a proceedings volume, but a special issue, having the same high publication standard of IJGT as any other. As author comment, please include the line «We are submitting this article to be considered for the issue related to the Combinatorial Game Theory Colloquium IV, held in Portugal in January 2023».

Bernhard von Stengel, Co-Editor of  IJGT 

Carlos Pereira dos Santos, Scientific Commitee of CGTC IV