This issue contains two sections. The first one is a symposium on human-computer interaction and games, edited by Karin Slegers, Lizzy Bleumers, Bernhard Maurer, Alina Krischkowsky, and Mark Blythe (2019). The second part consists of three regular submissions to the journal, as well as an obituary. We chose this structure, in order to remind our regular readers, who are often interested in other aspects of simulation and gaming, to look also into this area -because it is in fact one of our field's key connections to other crucially important communities. It includes the kinds of play that are extremely important to simulation/gaming studies.Disciplines that research and experiment with the interactions between humans and computers, humans and technology, or even animals and computers, have been interested in games and play for a long time. The archives of the key Conference on Human Factors in Computing Systems (commonly known as CHI; established in 1982), its spin-off CHI PLAY (since 2014), or the proceedings of the HiCSS conference (established in 1968) span over a long period. The broad spectrum of topics over the last decade has become the key venue for gamification research, with numerous essential contributions to the study of instrumental gaming and gamification in its various forms. The presence of that tradition in this journal has nevertheless been rare, until now.The three articles selected for this issue by the guest editors from a special CHI 2016 workshop represent varying aspects of how these two (or actually more) traditions interact and how they strengthen each other. The focus of all three is the application of games to do human-computer interaction (HCI) research. The first of them, "Using the SGDA framework to design and evaluate research games" by David Geerts et al. (2019), applies serious games to train passengers, hospital staff, and television viewers. The authors show that despite the varying contexts and projects, gaming simulation can provide very useful responses applicable for future development. Further, they argue for not just drawing from existing designs, but also for going for completely new ideas, in order to provide HCI with novel, original concepts invented and tested through play.With "Validity threats in quantitative data collection with games: A narrative survey", David Gundry and Sebastian Deterding (2019) discuss the ways in which results from a game can diverge from what is being researched. The central challenge is that even as games and simulations are simplified systems that may depict aspects of reality, that simplification in turn may lead the players to emphasize the wrong aspects of the