This article reflects on the effects of shared gaze visualizations on perceived social presence and non-verbal communication in online gameplay. We report on two case studies that employed shared gaze-based interaction in cooperative and competitive settings. These two case studies explored how players appropriate and utilize various gaze communication behaviors. In Study 1 we explored how a shared gaze visualization changes social behavior among players and collaborative strategies based on different combinations of gaze interaction and verbal communication. Study 2 followed a similar shared gaze approach but investigated its usage in different competitive game genres. Our study findings highlight the positive impact of shared gaze on collaboration and perceived social presence among players in both cooperative and competitive settings. This article presents a reanalysis and synthesis of the study findings, with the aim to identify differences and commonalities between cooperative and competitive use of shared gaze in games. To provide insights for designers and researchers, we discuss lessons learned of incorporating shared gaze visualizations in multiplayer games and illustrate related design potentials and pitfalls.