if u want a long series i have an idea but it might be a bit boring on the early part, first pick the best player for every civ, my first idea is having 1-2 days mirror tournament for every civ so we can have someone that can be considered the best option to play that civ, lets call that stage civil war, and then after every civilization consolidate their power under one ruler (winner of each civ mirror tournament) they will move to world domination stage, on this stage the one that "rule" the civ will keep playing the same civ until the tournament finish. The unique part regarding the world domination stage is that one can subjugate others. So how this work is that during the first round of the stage, the loser will be subjugated by the winner so the winner can bring the subjugated civ into the next round as teammate, however the teammate will be limited into dark age, the only way to remove the limit of your subjugated teammate is by subjugating more civ, so if u have 2 civ subjugated you will unlock feudal, 3 civ will unlock castle, and 4 civ will unlock imperial. However even if you subjugated more than 1 civ you can only pick one of them to accompany you and you can not change which player play which civ. Player can only be subjugated when they have no subjugated civ, if they have subjugated civ and then lost, the loser would lost 1 subjugated civ and it will be given to the winner. After the 2nd round (the 2v2 part because each winner from 1st round would have subjugated 1 civ) the way the bracket works will change, the admin will decide the seeding and then each non subjugated players will have a turn to pick who they will "invade" (basically pick their opponent) starting from the 1st seed then going down. If it is too long waiting the match 1 by 1, you can add the rule of the lower seeds turn will be removed once they got picked by a higher seed so the next turn will come faster, to make it faster also can limit the game into BO3 for each round in case some players keep going back and forth on the subjugated numbers or limit the numbers that can be subjugated into 4 and if defeating a 5th civ will make the 5th civ player get eliminated.