Finally got to clearing this! Feels like this nice mix of arcade and platformer, that offers a variety of options to make the game as hard or challenging as you like. The approach to difficulty and learning I enjoy as well. While I have thoughts about lives/points/items/continues I don't think I have much new to offer there so I'll skip that discussion.

What I like most is the approach to level design here, there's a real willingness to poke around in weird kinds of levels that still arguably fit as mario levels. There's levels that are transitory and take you into the sky. Levels that take a one-off entity and design a whole level around it. Levels that feel more like puzzle-exploration dungeons (6-5). Weirdly empty levels (7-fortress 1). Levels that slow the pace to a crawl of an explorative maze (7-9). Nightmare gauntlet with projectile hazards taking advantage of the space as muchas possible (8-1/8-2). And levels that genuinely evoke a feeling of fear - the autoscroll military levels in world 8!

While I think Mario's movement is not the perfect fit for some of these more explorative level types, they're still fun to play and it's still refreshing to play a Nintendo game that has an understanding of what level design can do to evoke different feelings and places. Genuinely, the inclusion of something like a "Ice World" or a "Fire World", as tropey as they've become, actually make sense in SMB3.

It's the kind of platformer design that you mostly don't see outside of the freeware or modding scene nowadays - this attempt at conveying some fictional world entirely through the goofy uses of blocks and strange platforming entities and obstacles.

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Probably the most interesting thing to me is the way in which this game sometimes feels like an early Zelda game, the way you check for secrets and nooks in levels, how SMB3's overworlds (for the beginner/unfamiliar player) are arguably dungeons with their lives structure (life-winning minigames excluded). Maybe late 80s/early 90s Zelda could be seen as an attempt at applying the kind of arcade mastery/discovery exemplified in SMB3 to a context that requires far less dexterity. (Unfortunately I don't think Zelda ultimately succeeded at developing an interesting core framework of expression, hence its reliance on many items/perfunctory puzzles and combat).

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My only point of critique with SMB3 (other than nitpicks, like enemy fireballs not hurting/affecting enemies, or some enemy movement patterns having that NES sudden-turn-jitteryness in a game where you usually only have one hit) - my only critique is that the game doesn't use its expression as an avenue for something higher. We get the impression of all these strange worlds with gigantic goombas or endless pipes - something with SO much interesting imagery and sensations, and then the game sticks on this awful save-the-princess framing story where every world ends with fiddly boss fights, a copy paste cutscene, and the same type of autoscroll levels (not without their merits, but this breaks from the theming the worlds worked so hard to build up).

As soon as the game achieves a run of a few interesting levels, it just as readily throws some card-matching minigame or a hammer bros. encounter at you.

Two interesting directions I think the series could go in from here:

1. Keep the overall structure, but axe the final castle levels. Instead, rework the back 1/2 or 1/3 of each world to feel like some kind of mechanical climax in the way that the leadup to Bowser's castle does. This would essentially be SMB3 but minus the stuff that I think doesn't make much sense with the game. Whoever does this can take notes from romhacks..

2. Axe the overall structure, and lean into a more open-world-level-select structure, focused on creating an evocative sense of place with each level, and a huge sense of the unexpected with what any one level might bring. Levels in levels, mini-world maps where you don't expect them. Super Mario Adventure, or something. Maybe you'd see levels like "Bean and Breakfast" from the SMW Romhack OOOOO... a level based on the Hotel dungeon from Anodyne! (https://youtu.be/-5LIz7JGO_I?list=PL1vXxNCYKhSptTEiHXL-1p-OSNvM1Knih&t=9381 )

And if you want to preserve some arcade-like tension, maybe the game is divided into lots of mini-worlds with a life pool that like, starts at 3 and can only hit 5 or something. idk!

As far as mario the series goes, #2 feels like what SMW or SML2:6 golden coins went towards. However, SMW exchanges evocative abstraction for more friendly, wide and 'realistic' levels - fun, but they end up about as exciting as the world design itself.. (satisfying to work through, but kinda plain)

And SML2 leans into an interesting/insane aesthetic but... abandons the mechanical fundamentals in favor of a kind of adventurey sorta thing.

Level-5 came up with a fantasy-fied variant of the Hundred Years' War on Jeanne d'Arc, their first attempt at grid-based tactics with 3D + animated cutscenes. The gameplay - mostly indebted to Matsuno's branch of SRPG (counter chance, position effects, path-to-point world map, etc.), also piles up quotations from others (BoF's transformations, Disgaea's heavy grind between missions, wearable upgrades, skill fusion and the obligatory RPS system) with questionable results. Even worse are the mechanics that favor one-note strategies, namely Burning Auras and Unified Guard (both requiring allies to stick close to each other), or those that detract from combat's pace, such as their team-to-team phases. That said, if the storytelling also feels like third-rate Tactics Ogre, they still managed to find room for their trademark humor & heartfelt vignettes.