Super Mario 3D World is a game developed by Nintendo EAD Tokyo and published by Nintendo. It is the sixth main installment in the Super Mario 3D series and the sequel to Super Mario 3D Land. The game follows Mario, Luigi, Princess Peach, and Toad as they attempt to rescue the Sprixie Princesses from the clutches of Bowser.

Here are a few trusted sources where you can download Super Mario 3D World ROM:

You can also purchase a physical copy of the game from retailers or online marketplaces. This option is available for both the Wii U and Switch versions.

It is generally legal to backup a game you own. Downloading files for games you haven't purchased is considered piracy.