This book constitutes the refereed proceedings of the First International Conference on HCI in Games, HCI-Games 2019, held in July 2019 as part of HCI International 2019 in Orlando, FL, USA. HCII 2019 received a total of 5029 submissions, of which 1275 papers and 209 posters were accepted for publication after a careful reviewing process. The 34 papers presented in this volume are organized in topical sections named: Game Design; Gaming Experience; Serious Games; and Gamification.