When completing a level in Super Mario Bros, a sequence of events will happen:
Mario will grab the flag
Mario and the flag will move down until the flag reaches a specific point
Mario will get off the flagpole
Mario will walk to the right until he reaches the castle door
Mario will enter the castle
This was what the developers intended for people to conclude when trying to figure out how the ending sequence worked. However, people figured out there was a little more to the ending sequence then meets the eye. The ending sequence (in a technical standpoint) really goes like:
Mario grabs the flag
Mario and the flag will move down until the flag reaches a specific point, OR until Mario reaches a specific point
Mario will get off the flagpole
Mario will walk right until he bumps into a solid block
Mario will be moved behind the background
How this TAS is possible
There are a few key things to mention with this system. Firstly, the flagpole base actually blocks Mario from moving down far enough to reach his point. However it IS possible to have Mario be grabbing the flagpole, AND have reached this specific point for a single frame. This is a well known glitch called flagpole glitch. The second key quirk with this system, which is what makes this TAS possible to begin with, is that when Mario is walking to the castle (aka walking right until he hits a solid block) The game never checks to see if the "solid block" is actually the intended type of block (a brick block) or if that block is even the intended block at all. All the game cares about is that Mario hits a solid block, no matter what it is, or where it is. This block is usually a block placed 1 tile to the right of the castle door, since it is a brick block, it takes the same texture as the castle, making it impossible to tell that it is solid rather then background by just looking at it. There also happens to be another solid block that spawns in the ending area: The flagpole base itself. If Mario was to bump that block however, he would need to be low enough to not snap up to the top of the flagpole base (at least 4 pixels down into the block). Sadly, this isn't possible by jumping from any intended area... But it IS possible by jumping from unintended areas. Or by not using a jump at all, and instead using the upwards velocity gained by bouncing off an enemy.
In short, when reaching the end of the level. I need 1 of 2 things to be the case:
Mario needs to be at least one block lower that the flagpole base (in the floor)
There needs to be an enemy Mario can bounce on in the space between the stairs and flagpole base
This trick is called a Full Flagpole Glitch (FFPG)
In some levels, this trick is pretty well known, and easy to achieve compared to some of the other levels. (8-2 for example)
But in others, it requires inhumanly difficult, precise tricks to pull off (1-1 for example)
Console Verification
I have verified this TAS works on console with the official Super Mario Bros. cartridge loaded, on unmodified hardware. I used the TAStm32 to replay it and cannot guarantee it will work with other replay devices (although it should)
Not every day I see something actually novel. Nice!
Warning: When making decisions, I try to collect as much data as possible before actually deciding. I try to abstract away and see the principles behind real world events and people's opinions. I try to generalize them and turn into something clear and reusable. I hate depending on unpredictable and having to make lottery guesses. Any problem can be solved by systems thinking and acting.
Hey there!
Not bad of an effort as usual, though I'm honestly not sure about the goal choice; probably suitable for Playground, but I'm sure judges will have a better idea of how to classify this.
Besides that though, I just want to start off by saying that the waiting around to make those Full Flagpole Glitches is not very exciting (though it is forced as per the goal), but I'd say otherwise that your entertainment wasn't so bad for the most part.
I'd like to point out that a warpless run which features more castles being skipped is available (although unlisted, I found it on the Super Mario Speedrunning (8-bit) Discord server):
Link to video
You can also see in the 8:09 timestamp that the runner, Losalex, travels to a further spot in World 4-1 to transform Spinies into Koopas faster (and also uses two Koopas instead of one).
Also, unless "avoid taking damage" is a secondary goal for you, 1:48 of this video shows that with the help of a Spiny, you can clip through the ground faster by clipping slightly and taking damage.
I don't think you'd need to worry about the smaller details though, since Super Mario Bros. personally has a lot going on beyond that. What matters is you played through it all very nicely, and with that, here is my Yes vote. :)
Currently dealing with serious IRL conflicts, so I won't be as active... But I'm still (hopefully) available on Discord to respond to questions or concerns.