Since I have more people than expected, the mechanism will be as follows:
I'll randomly make 2 leagues of 20 people each. After 19 rounds where everybody faces against everybody, the Top 6 players of each group will classify to a Final 12-people league, and after 11 more rounds we will see who the winner is.
Randomized list:
From 1 to 20 : Group A
From 21 to 40 : Group B