Take Wolfenstein 3D (1992) as an example. Genre defining game, no question.

Spear of Destiny (also 1992) is not only more of the same game, but an entire new game worth of new content. Great, but it's not part of any conversation.

Then came Doom (1993). Genre defining game all over again, no question.

On the other hand, you have Death Stranding (2019) and Death Stranding 2 (2025). Why did it take six years to make more of the same game?