This game is great, but I feel sadly its never going to be finished, its impossible, the Dev is beyond the pale ambitious and ambitiousness has killed so many games on this site, trying to make completely separate storylines within the same game, its going to take ages for the narrative to advance with the Dev having to perpetually advanced each of those storylines one at a time.
Why make all those other storylines if the name of the game is 'The Last Challenge'? It feel outside of the original storyline, that theme is going to be forced on the backburned as those other storylines will keep the MC away from home to some degree. Also the delay to the advancement of the narrative is going to be so utterly painful, in time its going to be likely a couple years wait between updates to all the individual storylines.
What I feel should happen is the Dev should put those plans on the backburned and just proceed with the original storyline, and when they'll be done with it, they can go on to recreate the other storylines with different MCs and their own specific games or at least even if they keep the same MC as alternate 'what if' stories just at least give each their own game to avoid the inevitable out of control game size growth.