Nintendo announced a 35-player online battle game for the Nintendo Switch during the Super Mario Bros. 35th Anniversary Direct stream. This is a Mario Battle Royal game. Nintendo probably could of make the game playable with 100 players. This game will only be playable from October 01, 2020 to March 31, 2021. You will need a Nintendo Switch Online membership.
Here’s the description from Nintendo:
Super Mario Bros. 35: Welcome to Super Mario Bros. … with 35 players! In this competitive online battle game, 35 players will compete to be the last Mario standing … or running. Enemies defeated will be sent to other players’ courses, but that also works the other way around! Players can activate special items to try and outpace their opponents. Super Mario Bros. 35 launches on Oct. 1 as a digital-only game exclusive to Nintendo Switch Online members.* The game will be playable until March 31, 2021.
Here’s the announcement trailer:
You can visit the official game page here.