NunuXD
First of all my English is horrible so forgive me the mistakes and this is going to be a really big comment: Your story is amazing and reuses a trope that has been sold out for a long time so it's a 10 for creativity, honestly this fight will be epic and if you like, this moment is perfect for some things for example: 1) Epic villain speech: something about the duality of Herobrine and Notch and a hint about the possible history between the two (like the brothers who created Mine or the god who split up and created a world to have company and something to do). 2) Implement the setting of being able to use and share metapowers BUT don't forget the off button as I see it what makes the game awesome for mutants is the taste of normality and the opportunity not to get screwed by its powers. 3) In the aftermath of the fight no matter who wins (notch/Herobrine) is an opportunity to unleash the resource of creation ce mods, a way of fun and arming players for the next invasion. Last but not least I'm curious to know the next game and an idea if you haven't already thought about it and that in every game there's a war between nocth and Herobrine and whoever wins sets the tone for the next game (whether it will qualify for all ages or not) for example if Herobrine wins this war the next game is something like Resident evil or Bloodborne but if notch wins do something like Pokemon or Zelda.
Make a dramatic entrance for herobrine. Make it like the players were winning when a few more ender dragons apearred with herobrine riding the front dragon and an army of mobs following them. It will be fun to see the players faces. Just suggestion by the way. One of the best books I have ever read. Makes me anticipate tomorrow for next chap
what if you made it a series of games where a part of Herobrine's consciousness is in the games Alex makes soon and act as the villain in disguise eventually leading up to the last game where his consciousness comes together forming the ultimate villain as he grew stronger through the games. Maybe you could allow them to access their characters throughout the games but can only access them once and when they die that have to spectate everyone else fight? By the way, the story is really good its actually one on my top 10 favorite novels list now.