I'm looking for a protagonist who embodies the ideal that nothing is impossible. Novel or fan fiction. I'm specifically looking for a scenario where the protagonist has the mindset of a man willing to challenge gods and trample hell. Like instead of accepting someone's death, they decide to research the afterlife, succeeds, threaten to nuke the underworld, usurp Hades, finds out that loved one has already reincarnated or sent to heaven, research souls, finds the Wheel of Reincarnation and Heaven, blackmails God, learns God is an idiot that can't do his job, MC makes time machine, then finally stops loved one's death and acts like nothing ever happened...
Sovereign of Judgement. The MC doesn't really use much tactics, he just charges in with his suicide squad. I'm not sure if this is what you're looking for. Divine Throne of Primordial Blood also goes this route since the MC is a researcher in a xuanhuan/xianxia world (I can never tell the difference between these two). Isaac maybe.
Definitely No Game No Life if you've not already read it P.s. this was one of the first novels I read so I'm not sure if it's actually as good as I remember. It definitely fits what you're looking for though.
Hmmmm. Randidly Ghosthound over on RRL is a bit in line with that. His wold gets saddled with a System apocalypse and he decides pretty quickly that he absolutely is not okay being under a damn System, and swears revenge against whoever made it. Some of his relationships with others even fall apart because of this, with them looking for ways to survive under the System and him being deadset on overcoming it. He really does have the mindset of "challenging God" from pretty much the get-go, and only reinforces that mindset as time goes on. Experimental Log of the Crazy Lich is about a nutjob lich that wants to subvert the Gods of his world and establish a system of law and order in their place. He also has a "challenging God" mindset. Rather, he's challenging everything about his world.
Emperor Domination. Might fit to your criteria. it's not reincarnation nor transmigration.. but still he turned the place where he go upside down.
I want to see what gets posted, as I've read most of the ones posted so far and trashed most of them from my list for various reasons ...
Everyone Else is a Returnee: 1000 years training for the Great Cataclysm, alone.Toaru Majutsu no IndexPS:Nice description.
Goblin Kingdom, King of the Battlefield. probably more in my reading list but those 2 come to mind with standing against gods and doing whatever they have to no matter what to achieve their goals
This is the very first thing that entered my mind as well. Not only does the MC of Everyone Else is a Returnee do 1000 years of training...he's basically willing to go against every single group that wants to fuck with his ability to live, heh. Now for my other recommendations, lol: Ascendance of a Bookworm (NOTHING is gonna stand between her and her books, lol) Ex Strongest Swordsman Longs For Magic In Different World - As far as I know he doesn't let anything get between him and what he is aiming for (magic), heh. Isekai Tensei no Boukensha - The MC doesn't let things stand in his way...though it's also not like he goes around researching a lot of things. It might be up your alley, though. The Consequence of Being Summoned Simultaneously from Another World - As far as I am aware, there's no actual researching going on...but this dude most assuredly don't let anything in his way stay in his way. The Spearmaster and the Black Cat - Shuya is amazing in this respect. He's not a research nut or anything, but anything that gets in the way of him or the ones he loves..........................gets messed up, heh. It should be noted that Shuya is a perv though, but he's definitely open about it...and he does get plenty of women (but it doesn't go into detail about their escapades). The Skill Maker - It's difficult to say on this one, as the dude starts out having some trouble...and he's kinda working against the odds, but yeah. It might fall into this category. You'll have to either find an aggregatorsite for it, or look at an internet archive in order to read it, though. =\ I Never Run Out of Mana - He doesn't curbstomp every single thing under the sun that gets in his way once he gets power, but he definitely stops taking shit from people at least...and he finds ways around the limitations that he's faced with by society, as well. World Teacher – Other World Style Education & Agent (WN - The MC in this one will erase those that are antagonistic towards him...but he doesn't exactly crush every single thing in his way with force. He's better off working from the shadows, after all. If you want to include VRMMO series then there's also these: The Legendary Moonlight Sculptor - the MC doesn't let anything stand in his way, if he has to go through it to get to the other side that is Ark - The dude maay have setbacks, but he gets revenge on anyone and everyone that fucks with him and whatnot, so I think it might fit it Ark The Legend - sequel to the previous link I'm sure that not all of these meet the requirements perfectly, but hopefully at least some of them do. ^^
Randiddly isn't really worth reading in my opinion. The author writes a story with high tension and no release. Everything is always on a knife edge to the point where the series ends up frustrating rather than fun. He's even willing to weaken the character just to keep it there.