**1.1 Important terminology**

In this chapter, we use the term *game-based intervention* to speak broadly of game-like experiences and the ways they are applied for non-entertainment purposes such as education or evaluation. Within this broad conceptualization, there are several important terms: game-based learning (GBL), game-based assessment (GBA), gameful design, gamification, and COTS games. GBL, also referred to as serious games [8] occurs when a game is used for the primary purpose of learning [2]. Similarly, GBAs are evaluations that take place within the context of a game expressly designed to identify specific skills, traits, or behaviors [9]. In contrast, gameful design and gamification are design strategies which incorporate game elements into new or existing assessments respectively; typically for the purpose of engaging and motivating individuals [2, 9]. Thus, a thorough understanding of game design is requisite to the development of effective GBLs and GBAs as these interventions use the full suite of game attributes. For example, see [1] for a taxonomy of game attributes. As a result, developing GBL and GBAs entails considerably more expertise and resources compared to incorporating game elements through gamification or gameful design. A potential solution to the resource-heavy nature of game development is the utilization of COTS games. Designed by game developers, COTS are most commonly designed for entertainment purposes and are available for purchase by a vendor and can be used almost immediately after purchase [10, 11]. COTS games offer a reasonable alternative to the time and resource intensive commitment to develop one's own games [12, 13]. GBL, GBA, and COTS games are explored in more detail in the following sections.
