The Big Block DLC is a season pass that is available to purchase now from Nintendo eShop for $9.99 (£8.99).
The DLC pack initially adds two new offline modes — CPU Battle, which allows players to compete against 98 CPU players and Marathon, a challenge to clear the most lines and score big.
Buyers will receive a further offline mode when it’s released later this year, Nintendo said, with more details to follow in due course.
Since the modes are entirely offline, purchasing the DLC makes Tetris 99 available to those without a Nintendo Switch Online account for the first time.
Finally, Nintendo has confirmed a third Tetris 99 Grand Prix event will be taking place between Friday, May 17 at 9am CEST and Monday, May 20 at 8:59am CEST.
This time round, participants who earn 100 event points during the three-day period will unlock an in-game theme inspired by the original Tetris Game Boy game.