1. Skill-based -
2. Chance-based -
The problem with these two strict categories is that no skills games are pure skill. It also contains luck in it. How many % skill and % chance should we put the game into a skill or chance-based game?
You can compute the skills but you can't on the luck..
Just give you best to improve your skills so you don't need to rely on your luck all the time.
When you are a skilled gambler, you are likely treating what you do as a job, you are professionally handling it, and you keep a record of your performance when gambling, but most importantly, you choose the right game for you that does not belong a luck based games. (with house edge).
This situation also makes a game like a poker illegal in some parts of the country but legal for the rest.
Poker is gambling, a certain country does not choose a certain game to legalized or not, if its illegal the they regulate it generally and they make gambling illegal, just like in China I guess.