  Kingdomino is a board game designed by Bruno Cathala and edited by Blue
Orange since 2016. The goal is to place $2 \times 1$ dominoes on a grid layout,
and get a better score than other players. Each $1 \times 1$ domino cell has a
color that must match at least one adjacent cell, and an integer number of
crowns (possibly none) used to compute the score. We prove that even with full
knowledge of the future of the game, in order to maximize their score at
Kingdomino, players are faced with an NP-complete optimization problem.
