Given your love for the franchise you might want to check the book "Game Design Companion: A Critical Analysis of Wario Land 4".
It's a 600-page in-depth analysis that covers every aspect of the game's design.
Bought it, read it, loved it. It's really a great book for people wanting to really dig into video game analysis. It's probably important to note that the book is intended as an example of his style of critical analysis, to teach others how to look at a game with strict objectivity. It's not a platform for him to gush about Wario Land 4, even if it reads that way sometimes.
My favourite parts are "Premise and Interaction set in context" and "Wario: A Personality Profile"/"Mario and Wario - A Character Comparison".
The former goes into detail about how the player's actions provide a narrative for the game, when projected against the context provided by the game. Not in a linear "Wario hit the enemy and then collected some jewels" way, but in a way that reveals the personality and intent of the game's actors.
The latter extends that by providing an analysis of what the game's mechanics and the interplay of game elements says about Wario as a character.
Edit: There's also some interesting mentions of the symbiosis between the player and the player avatar; each one providing separate halves of a full character.
This is how immersion works; you integrate the player's perspective and agency in a way that meshes with the gameworld.