If anyone else is a fan of the original Deus Ex, one of the writers for it, Sheldon Pacotti, has been writing science fiction for years:
Haven't had the chance to read anything by Chris Todd yet (the writer/curator of all the snippets you come across within the game, as opposed to the plot itself), but I remember enjoying his in-game style a lot too at the time.
Kojima's final game at Konami was Metal Gear Solid V. After he left, Konami shrugged and made Metal Gear Survive. Suffice to say, the non-Kojima metal gear was a flop. Itagaki is another example. He's the creator of Ninja Gaiden, and also ended up leaving Team Ninja after a dispute. His final game was Ninja Gaiden 2, their first game was Ninja Gaiden 3. And again, the reception went from positive, to flop.
And to be clear it's not like these series waxed and waned. Every single Metal Gear game with Kojima received exceptional praise. Similarly for every single Ninja Gaiden game, to a lesser degree. Then they leave, and the series collapse. Obviously far more people work on these games than just the singular name, but if most of these people were replaced with somebody of a similar skillset, the final product would be largely unchanged.
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Reception for Metal Gear Solid V: https://en.wikipedia.org/wiki/Metal_Gear_Solid_V:_The_Phanto...
Reception for Metal Gear Survive: https://en.wikipedia.org/wiki/Metal_Gear_Survive#Reception
Ninja Gaiden 2 Reception: https://en.wikipedia.org/wiki/Ninja_Gaiden_II#Reception
Ninja Gaiden 3 Reception: https://en.wikipedia.org/wiki/Ninja_Gaiden_3#Reception
Of course you can say "well if this is true it only shows that Kojima can attract the best talent to work for him" and sure, that's probably true. But then we can't claim it's all completely Kojima doing the work.
Go back to the original 1987 Metal Gear on the NES and you'll find 0 overlap except for Kojima. Kojima was a new hire at the time and thrust onto a completely new team on a project already in development. He dramatically shifted the direction of what was being built, and what was born was Metal Gear. And, as would become a recurring pattern for every single title he's been involved in, it was met with phenomenal reception.
I think the truth is somewhere in between. Kojima benefits from relying on a highly skilled team that deserves more credit than they get. At the same time he probably doesn't get enough credit for attracting that talent and creating an environment they can flourish in. If that were easy then anyone would do it.
Hidetaka Miyazaki,for example, is one such “auteur game designer” and it’s very clear when he has had his influence on a game.
Just compare Dark Souls 1 or 3 (which he worked on) to Dark Souls 2 (which he didn’t work on) and Bloodborne (which was created by Miyazaki in parallel with DS2) and you’ll see that his influence on games that he has a direct hand in is massive.
Or for something more relevant, the first and only Metal Gear game released after Kojima was fired by Konami - Meta Gear: Survive - was an unmitigated disaster. Metal Gear Solid 5 was unfinished and flawed, but there’s no denying that it had Kojima’s flourish on it.