The best theory I've ever heard regarding the mysterious way that Mario games get made runs like this: deep inside Nintendo's development structure, there are people working on Mario stuff all the time, irrespective of specific games. They're just toiling away in the Mario mines, churning out endless ideas for anything and everything - bosses, collectables, enemies, traversal gimmicks, ghost house hallways, the works. Mario is always being made, and practically any idea can lie within its remit. Mario is games, and all games - all toys, all play - can eventually be folded into the mix.
That certainly explains a game like Super Mario 3D World - yet another Mario title where each new level can be trusted to throw in a one-off idea that's forgotten seconds later. 3D World has a story, but as ever, it drifts into the ether the moment you take your first jump. It has world themes - desert, ice, grasslands - but they're largely ignored as you hop between pools of bizarre brilliance that defy easy categorisation. Autumn, water parks, the circus: each level takes you somewhere different, while every minute of play spools outwards in a friendly 60fps jumble of nutty concepts - perhaps nuttier here than ever before. And yet! And yet that famous Mario coherency still rules - because everything you encounter in a Mario game reminds you of something else you encountered in another Mario game. Because Mario is games.
Exhibit A: We need to talk about the goomba shoe. You know, the goomba shoe from Super Mario Bros. 3, a single-shot power-up that appears only in level 5-3, where you find a goomba stomping around in a large green boot - a boot you can steal.