The game’s objective is two-fold:
IYou can play for fun with other users and make new friends;
IIYou can join a League and play for a period of time in competition mode.
In the first case (Play for Fun), your goal is to practice the game and earn XP points, move up to higher levels and show your value.
In the second case (Play for Rewards), your goal is to play seriously, reach the top of the leaderboard and qualify to win a reward.