Abstract
Darwin’s Demons is a video game that incorporates evolutionary biology. It features a population of enemies encoded by diploid digital genomes of quantitative trait loci. Each round of gameplay is modeled as a generation in which a new enemy population is produced using tournament selection with replacement. Each parent provides a chromosome produced with free recombination. Mutations are then drawn from a Gaussian distribution. Enemies gain fitness by shooting close to the player and spending time near the bottom of the screen. These conditions produce rapid rates of adaptation to player strategies. Ultimately, Darwin’s Demons allows players to observe (and sometimes exploit) evolution through the course of gameplay.