To join friends online in Mario Kart World, you need to do the following: Make sure all players have a Nintendo Switch Online Membership. You can't play online games without them. One player goes to the main menu of Mario Kart World and selects "Online Play".

It might not have all the features of solo, but you can play Free Roam splitscreen in Mario Kart World.

The tracks in Mario Kart Word are the real stars in the game and the shiniest one is the Rainbow Road track. The mesmerizingly colorful track is something out of this world — literally. Unlike all the other tracks in the game, Rainbow Road is a secret one, but luckily the path to find it is pretty straightforward.