Only that liking games is immature -- which doesn't imply that not liking games automatically qualifies one for maturity (it's a necessary, but not sufficient condition).

Nor does it imply that I and those who share my opinion consider themselves mature (a non-X person can still make claims about what constitutes being X, and those claims can even be perfectly correct -- doubly so in a subjective, non-well defined, topic, like what constitutes maturity).