It's really cool seeing the NES and SNES footage together like this. You went out of your way to do Super Mario Bros 3 and this challenge justice! Such a thorough, well-thought out and excellently put together list. Many of these levels are surprisingly unforgiving and I agree with all of your placements. I forgot that the Coin Ship had a Boomerang Bros fight, so that's awesome to see you include that. Definitely was a blast watching you go through the game like this. Looking forward to seeing some more SMB3 content from you!

7-4 was the bane of my existence on the GBA version growing up

Your commentary helps me recognize things I didn't consider in the game design that the developers likely intended for difficulty curve and things like that. I haven't tried to play as small Mario before but now, I really want to give this a shot when I have some time

The difficulty of World 7 in SMB3 is insane. In terms of overall difficulty, it might even surpass World 8. I didn't clear SMB3 without using the Warp Whistle until I was an adult.
Thank you so much for creating such a detailed explanation video!

World 8 is supposed to be like Mordor, dark and sooty.

I never knew Ludwig had a weird hit box

7:00 You can pause and the plants still move.

21:38 6-7...

5:56 that Ice area had the coolest theme music.

I HATED 7-8 even WITH power-ups!

I love Mario 3! It was the first game that really challenged me and definitely helped me fall in love with gaming

0:40 THEY EXPLODE!?!?!

If only modern 2d Mario games could have this same level of difficulty. Part of what makes Mario 3 so good

This feels like a shoutout to my childhood since All-Stars was my first game, and I didn't have a manual to learn the controls. My friend showed me the warp whistle location, but I was so bad at this game that I basically was always Small Mario. I didn't beat this until years later when I finally learned the run button and how to use the powerups.

My guess before watching the video, was 7-8 for #1. And for the same reason, that enemy plant shooting fireballs was quite a wall without power ups. I always rely on a power up to beat this level, seriously.

My guesses have been on point on most of your videos, since these were my childhood games and already have the knowledge of all the levels. No surprise that 7-8 being #1, such a brutal level just playing as small Mario.

That's the level I'm having a difficult time with as a kid, but now that I'm older, I don't have a problem with it at all 7:55

I love how almost half the list is World 7.  A testament to the merciless brutality of that area.  Ludwig is most definitely the Kintaro of this game's boss fights.  Dude was actually broken when you get right down to it.  That was the only rage quitting I ever did with this game.  I understand making bosses difficult and all that, but Ludwig was a walking cheat code.

Side note: seeing the two versions side-by-side reminded me how much I hated that they didn't keep the different colored airships in All-Stars.  Such a small detail, but I really liked that feature of the NES version.

23:57 introduces you to the equivalent of a Glock Switch

17:58 I'm actually really surprised by that. Maybe I just don't remember because it's been a long time since I played but I just don't remember having that inconsistent hitbox with Ludwig and when I grew up in the 90s I played Super Mario all-stars. I didn't play the NES one that much.

8:51 without that cloud item that lets you skip levels, this stage is a requirement. It's level 5 that's optional. Level four only becomes optional if for some reason you game over in World 7 after you've completed the first fortress already and you can get through that gate that was already opened after completing that fortress.