DotA is one of the most attractive and influential MOBA games, which has been popular in many countries for over 10 years. It was designed for fun at first, however, after the emerge of DOTA2 it soon became the highest prize e-sports game. This paper analyzes the evolutionary changes of the DOTA2. The game refinement measure is employed for the assessment of game sophistication of DOTA2 series. The analyzing results show that the rules of DOTA2 have regularly been changed in its history to maintain an appropriate range of game refinement. We clearly see two directions during the evolutionary changes which are the skillfulness and popularity. Thus, the analysis makes it possible to overview these evolutionary changes of DOTA2 and find some drawbacks to be improved.