MarioNES 1.5: The Lost Update That Changed Super Mario Bros. Forever

The "Minus World"

: Perhaps the most famous "glitch text," the Minus World (World -1), occurs through a collision bug, though the text is simply a blank tile where the world number should be.

The "sticky friction" is controlled by a single byte at $07F5. In MarioNES 1.5, that byte is #$2C. In the original, it is #$13. This change is too subtle for a typical early-2000s hacker to notice.
The Lakitu respawn code contains a JMP (jump) instruction pointing to a garbage memory address that doesn't exist on retail builds.

Three reasons:

The game had saved. The glitch was stable. For now, the Kingdom was safe.

Mariones 1.5 Best -

MarioNES 1.5: The Lost Update That Changed Super Mario Bros. Forever

The "Minus World"

: Perhaps the most famous "glitch text," the Minus World (World -1), occurs through a collision bug, though the text is simply a blank tile where the world number should be.

The "sticky friction" is controlled by a single byte at $07F5. In MarioNES 1.5, that byte is #$2C. In the original, it is #$13. This change is too subtle for a typical early-2000s hacker to notice.
The Lakitu respawn code contains a JMP (jump) instruction pointing to a garbage memory address that doesn't exist on retail builds.

Three reasons:

The game had saved. The glitch was stable. For now, the Kingdom was safe. MarioNES 1.5