Making Games in a Crossover World

After transmigrating to a world of mixed anime and manga, he returns to his old trade and starts developing games, recreating all kinds of games from his previous life in this world.

Slay the Spire, The Binding of Isaac, Hollow Knight, Dark Souls, Sniper Elite, Nioh...

From pixel-art indie games to major single-player titles and open-world games,

players gradually realize that the games this guy makes keep getting harder. Why is that?