This book constitutes the refereed proceedings of the 6th International Conference on HCI in Games, held as part of the 26th International Conference, HCI International 2024, which took place in Washington DC, USA, during June 29 - July 4, 2024.  The total of 1271 papers and 309 posters included in the HCII 2024 proceedings was carefully reviewed and selected from 5108 submissions. The two volume set of HCI-Games 2024 proceedings were organized in the following topical sections: Volume 14730: Part I: Game Design and Gamification; Part II: Game-based Learning; Part III: Games and Artificial Intelligence Volume 14731: Part I: Advancing Education Through Serious Games; Part II: Player Experience and Engagement