MM54321 in an Ice World Adventure is MarioMario54321's 6th video and stars himself.
Story: MM54321 goes to the pool in the Castle Basement and is warped to an IceDesert. After a while, he goes back to the castle.
Characters: MM54321, SnowBird, IceDesert god, and IceDesert Bully.
- This is the first appearance of MarioMario54321.