The paradox of the optimal flow experience (Engeser & Baumann, 2016) also makes gamification harder in reality. For instance, in Disneyland gamification, the real-time productivity of each employee was displayed on the leaderboards, and it became clear that this unexpectedly enforced them to compete with each other and destroyed their collaborative culture (Lopez, 2011). Omnicare, an American pharmacy and healthcare company, introduced a gamified customer relations system to reduce response time, but its employees felt very uncomfortable with covert monitoring of their performance, resulting in a higher turnover rate and accordingly lower customer satisfaction (Liu et al., 2017). Callois ( 2001) thus claimed gamified systems are too hot when they provide only a hedonic experience, or too cold when they exploit only productive behaviors, which suggests an appropriate gamification strategy needs to set the right balance for both the employers and employees. The focus of this study is to figure out the "Goldilocks" gamification conditions, in particular, for the manufacturing workers at Hyundai Motor Company (HMC).Recent research sheds light on workplace gamification (Funk et al., 2015;Korn, 2012;Warmelink et al., 2018a), but manufacturing workers are still reluctant to fully adopt the gamified system (Kim, 2018). The reason behind this is previous workplace gamification forced workers to focus exclusively on productivity performance (e.g., accuracy, task completion time) through reward systems (e.g., points, ranks). These pseudo-performance measurements eventually provoke the "give-and-take" feeling in the worker's mindset of what they had acted on (Kohn, 1999;Kramlinger & Huberty, 1990;Nicholson, 2015), so organizational moral problems would follow accordingly (Cable et al., 2013). Janakiraman et al. (1992) maintained, in management studies, that such performance-focused evaluation cannot fully assess the worker's effort level, in the sense that as the workers shift their efforts from a subset of tasks which they consider useful and constructive to a subset that they think "gives" or "returns" the highest benefits of being useful and constructive (i.e., subjectively more valuable; Baker, 1992;Prendergast, 1999). A well-known consequence of this approach is for the worker to be often hooked into off-the-job opportunities when not evaluated or observed (e.g., the Hawthorne effect; Stand, 2000).In this sense, many gamification studies (Deterding, 2012;Mekler et al., 2017) claimed that intrinsic motivators should be included. However, the conventional gamification approach has simply considered this by providing more enjoyable and exciting gaming experiences, believing that the game-play itself might serve for promoting one's intrinsic motivation to play. Unfortunately, the hedonic adaptation effect (i.e., the tendency for humans to quickly return to a relatively habitual level of happiness despite positive or negative experiences; Diener et al., 2009) thwarts this game-play motivation from lasting longer. Some intrin...