The worlds' order is going to be as follows, with some reasons why:
1st - Danmachi (current).
I started here to build some hype like "What will he do once he returns here?" or "Will he ever return and accomplish certain things in this world?".
2nd - Hollow Knight.
No dragons are present here. It is purely for character development and better weapon handling. Remember that some bugs held unconventionally shaped nails, like Hornet's nail that has a silk thread attached to its handle like a needle. Others used entirely different weapons, like Atra, who wielded a jagged machete, Garro, who used a glaive-looking, long weapon, Cloth, who hefted a large club over her shoulder, or Galien, who threw spinning scythes at you. There is also a power-up I'm planning for him to gain from there and certain game mechanics as abilities. The power-up will not be permanent in the sense that it will have a timer upon activation and another for a cooldown. It won't give him an immense power boost, more in line with giving him a little bit of extra edge. The power-up will also have a penalty on excessive use. We will discuss the extent of its effect and penalty when Nephelont has finished what is planned for him in this world.
3rd - Ark: Survival Evolved. Specifically, the Aberration ARK.
Rock drakes are dragons, though considered impure by the DH skill thus giving almost no increase in physical aspects and none in mana reserves as they wield no magic of their own. And you can take into account that Nephelont is not immune to element radiation in his ancient dragon form. He will be limited on how many cryopods (2 to a max of 4. Nothing more than that) are allowed in his system inventory. As you may have guessed, only items he is wearing or storing in his system inventory are carried over to the next world. If he stupidly left an item out of his system inventory upon going to the next world, it's forever gone.
4th - Rising of the Shield Hero.
Anything I tell you will be more than a spoiler here. Just know he is gonna be one of the summoned heroes.
5th - One Piece.
Armament and observation haki are possible for him, but hardly conqueror's haki, as I will spin a randomizer once to determine if he ever awakens it or not. You will have to wait and see if he does or if he doesn't. "Haoshoku Haki is a rare form of Haki that allows the user to exert their own willpower over others. This type of Haki cannot be attained through training and only one in several million people are born with this ability." according to the wiki. So, it will be a 1 in a 6M-9M chance.
6th - Re:Zero Starting Life in Another World.
I will have some mercy on poor Subaru's soul. Oh, don't you worry, he is still dying once per arc at the very least. Mr. Nagatsuki Tappei has delivered his verdict on this matter.
7th - MHA.
I will skewer the canon. That's all I have to say about this one. No power-ups or extra abilities, unless you (the readers) wanted them to be.
8th - Eminence in Shadow.
Just some fun. Not much divergence from canon, still some divergence.
The thing that booked this one for me was the "I am atomic" moment in the anime. I mean, it was so good in the manga, but the anime took it to a whole new level. And the music, don't get me started on it.
9th - High School DxD.
Maybe, maybe not. Depending on what it actually goes like in its canon.
10th - Mushoku Tensei.
I read the manga until the parts where Rudy married Sylph. Any further is uncharted territory to me for now.
One thing I promise you though, Hitogami is fucking dead. The shitfaced asshole just annoys me a whole lot. If you knew me personally, you would know that I don't throw swear words or insults around for no reason, but this poor imitation of a life form is somehow capable of annoying me to no end, even if he wasn't there he just finds a way to be annoying. HE. IS. DEAD.
11th - Elden Ring.
I am willing to bend some rules and create my own lore since Elden Ring lore is in the air by default. Zorayas will be there, Radahn is gonna be even more powerful than he is already and a very major power-up for Nephelont is happening here. Search in the Elden Ring wikis: What is the primeval current? If you are curious. It is related to the power-up.
The reason why I put this here, in the very last spot before returning to Danmachi is because it is here. It is here where Nephelont has access to ancient dragons and some of the most broken spell schools in all of the worlds that come to my mind at the moment I'm writing this.
12th - The return to Danmachi.
I want to play with some of the characters, it just needs so much raw power to play with them and have no major consequences.