We're on hiatus for about a month while the DM for our 5e game is in India. He's also a player in my PTU (Pokemon Tabletop United) game. For PTU, we're only a couple sessions in. My players are exploring a secret underground mushroom forest. In a few sessions, they should be ready to meet the fairy ruler of this hidden land, the legendary Pokemon Diancie, who will task them to clear a dungeon, and defeat a Mimikyu that is trying to steal her power. Afterward, Diancie will be introducing the main plot of the game, which is that players can become champions of the gods (the legendary Pokemon) by impressing them, and be granted powers to help them complete their quest to journey to the end of the world.

That'll be the end of Act 1, or maybe technically the prologue, but it feels weird calling it that when it's going to be like 10 sessions, and then they'll emerge in the untamed wilderness to embark on their journey

That's also when I'll be able to have guest characters join. One of my players recently introduced to a friend of his that is a huge Pokemon nerd, and we really hit it off. I can't have a fifth player, because 4 trainers with 6 Pokemon each is already a lot for a TTRPG, so he's going to be a recurring guest every so often