The 8th International Conference on HCI in Games, HCI-Games 2026, held as part of the 28th International Conference on Human-Computer Interaction, HCI International 2026 (HCII 2026), took place in Montreal, QC, Canada, during July 2026.A total of 7435 individuals from academia, research institutes, industry, and government agencies from 94 countries submitted contributions to HCII 2026. Following peer review, 1463 papers and 360 posters (as short research papers) are included in the volumes of the HCII 2026 proceedings published just before the start of the conference.Two volumes of the HCII 2026 proceedings are dedicated to this year’s edition of the HCI-Games Conference, focusing on topics related to: HCI in Games (Part I): Serious Games, Simulation, and Training; Player Experience, Emotional Depth, and Game Psychology; Health, Well-being, and Persuasive GamesHCI in Games (Part II): Game-Based Learning, Education, and Gamification; Interaction Design, Accessibility, and Emerging Game Technologies