Nintendo Switch Online members who have downloaded the Tetris® 99 game can participate in the Tetris 99 MAXIMUS CUP online event from 5 a.m. PT on March 8 to 11:59 p.m. PT on March 10. During that time, win first place (you’ll see TETRIS MAXIMUS on the results screen when you do) as many times as you can. After the event, the top 999 players with the most TETRIS MAXIMUS wins will be notified, and will each receive 999 My Nintendo Gold Points. More details can be found by visiting https://tetris99.nintendo.com. Tetris 99 is free to download and available as a special offer for Nintendo Switch Online members.
Source: Nintendo PR