In first-person-shooter player-vs-player games, two teams of competitors navigate through a virtual arena while fighting one another to accomplish the gameplay task. Game developers frequently update and add virtual arenas, so gamers must constantly update and add to their spatial knowledge to remain competitive. Despite this, the way that gamers learn and use spatial knowledge during competitive play has yet to be investigated. I sought to qualitatively and quantitatively investigate this in a series of two studies—an interview study and a playtest study. In the interviews, gamers reported that they primarily learn and use the environment to gain an advantage over their opponents by seeking tactically advantageous positions and strategically planning for the gaming task based on their environment. In the playtest study, casual and esports gamers learned novel gaming environments in three different learning conditions (control, tactical cues, non-tactical cues) before they played a match on the map with in-game bots. Esports players out-performed casual players in their (a) in-game kills and deaths, (b) ability to identify their current location during the match, and (c) ability to recognize the environments that they had played in. Although learning condition did not significantly influence performance, qualitative data revealed that participants attempted to gather and use tactical information. The combined responses by participants from Study 1 (the interview study) and Study 2 (the playtest study) were used to describe the concepts of tactical spatial knowledge and tactical navigation. This information is a valuable addition to the gaming and tactical decision-making literature. It can be used by esports teams to identify potential future players and inform the future development of training exercises to improve the learning and use of spatial knowledge.