Uploaded June 2021 | Updated September 2026, 1 day ago

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Load your SMAS ROM in a hex editor.
Two addresses will be needed to be modified, to access 256 levels/worlds.

First address: Will be used to explore levels before 1-1. By default, it's "24".

0x2403D for US and JP ROM
0x2423D for EU ROM

Second address: Will be used to explore levels after 8-4.
There're eight bytes; 00 05 0A 0E 13 17 1B 20
Those in order, being the IDs for the first levels of each world.
If "00" there is changed, then 1-1 (and the levels after that) will become a new level.
Changing the next byte (05) will change World 2-1, the next one (0A) will change 3-1 and so on.

0x2411C for US and JP ROM
0x2431C for EU ROM

In the video, the addresses 0x2403D and 0x2411C are set to (in order):
0:00 - 0F and 00
1:40 - 18 and 00
3:40 - 1D and 00
5:33 - 24 and 25
6:40 - 24 and 30
8:16 - 24 and 34
10:42 - 24 and 39
13:15 - 24 and BE

List of levels and their IDs:
ia601407.us.archive.org/34/items/smb1sneslevelids/smb1sneslevelids.txt