This book constitutes the refereed proceedings of the Second International Conference on HCI in Games, HCI-Games 2020, held in July 2020 as part of HCI International 2020 in Copenhagen, Denmark.* HCII 2020 received a total of 6326 submissions, of which 1439 papers and 238 posters were accepted for publication after a careful reviewing process. The 38 papers presented in this volume are organized in topical sections named: designing games and gamified interactions; user engagement and game impact; and serious games. *The conference was held virtually due to the COVID-19 pandemic.