## 2 Brief Introduction to TAM Model  
Information Technology (IT) has engulfed a lot of fields in which researchers are continuously traversing to find practical systems for the user. There exist many IT models which need to be fixed and enhanced in their performances, such as Technology Acceptance Model [30], Motivational Model [31], Theory of Reasoned Action [32], Model of Personal Computer Usage [33], Theory of Planned Behavior [34], and Unified Theory of Acceptance and Use of Technology [35]. However, over the past few decades, TAM has been successfully extended in many research disciplines and has given relevant implementations, exemplifying its potential significance to understand the user behavior towards adopting information technology systems. At the early stage of the TAM model, the actual system usage can be predicted by stimulation of innovative ideas and analyzing specific effects on the external variable, such as system features, capacities, etc. [30]. It is also proposed that user encouragement is comprised of three aspects that can explain actual system usage: perceived ease of use, perceived usefulness, and attitude. In this model, the attitude was used to determine the perceived usefulness and ease of use, which seems to be the strongest predictor for a user to approve or refuse a system. In addition, many external variables influence perceived usefulness and ease of use. Further, Reference [30] proposed that perceived usefulness and ease of use are the most significant values for each user to determine, either to support the system or not. Although the TAM model was the first proposed model which has been progressively modified by including many other parameters, such as behavioral intention (BI), which is added to the basic model of the TAM [36]. Since then, it has emerged as a leading model in the understanding of adoption of an IT system, and it is also considered the most suitable to examine the popularity of online games.  
Online gaming has become one of the most potential benefits for the development of IT systems. As gaming requires high-end graphics and high-speed Internet to play online games with other players, the IT industry has begun to tackle complex problems to solve graphics problems and provide a smooth, reliable, and robust system. It has significantly changed the behavioral pattern of all users in utilizing their leisure time [37], not only in teenagers, but even in elderly people [38]. Moreover, with information technology, mobile online games are becoming much more influential than PC games as it is easy to carry a smartphone, rather than a PC, so people spend most of the time on smartphones. So, people play online games on their mobile device more frequently as compare to PC during traveling, etc. This has contributed to a great deal of work to grasp online games' success. In Reference [39], attempts to discuss success of online games generates from a fun-oriented technological perspective, by implementing social influences and flow experience as beliefs-related constructs in a TAM model to anticipate acceptance by the users. In Reference [40], it is concluded that flow experience is much more essential than enjoyment for influencing the adoption of mobile online games by customers. Furthermore, the study revealed gender as a main moderator for mobile online game. Afterward, [PERSON] [31] developed a generic research model that includes flow, social interaction, and enjoyment, based on the TAM model, which identifies the reasons that attract people to playing online games. In Reference [41], it is also indicated that confidence is another leading factor for online mobile games.