Tetris 64

Tetris 64 (テトリス64) is a puzzle video game developed by Amtex and published by SETA for the Nintendo 64. It was released exclusively in Japan in 1998, and came packaged with a unique accessory, the "Bio Sensor", which alters the game based on the player's heart rate.

Gameplay
Tetris 64 features three modes of gameplay. The main "Tetris" mode features standard Tetris gameplay, with players attempting to clear lines using tetriminos falling from the top of the screen to avoid their play area becoming full. In "Giga Tetris", larger tetriminos will fall in addition to the standard sized pieces; when used to clear a line, they will break into smaller-sized pieces that fall to fill the gaps below. Both modes support simultaneous multiplayer for up to four players.

The "Bio Tetris" mode utilizes an accessory called the Bio Sensor, which was developed by SETA and packaged with copies of Tetris 64. The Bio Sensor connects to the system through the Nintendo 64 controller's expansion port, and analyzes the player's heart rate using a clip that fastens to the player's ear, with the game adapting based on this information. Bio Tetris offers two variations which utilize this feature: Normal, which lowers the game's difficulty when the player's heart rate rises, and Reverse, which instead increases the game's speed with the player's heart rate. Unlike the other modes, Bio Tetris only supports up to two players in multiplayer. Tetris 64 is the only Nintendo 64 game compatible with the Bio Sensor.

Notably, Tetris 64 exclusively uses English text in its menus, despite never being released outside of Japan.

Reception
Tetris 64 was praised for its multiplayer mode, as it was the only Nintendo 64 Tetris game at the time to support multiplayer for four players; The New Tetris would later incorporate this feature when it released the following year. Conversely, the game was criticized for its poor graphics and simple backgrounds, which could not match other Tetris games released for the same console such as Tetrisphere and Magical Tetris Challenge.

Some commentators have drawn retroactive comparisons between the Bio Sensor's functionality in Tetris 64 and the cancelled Wii Vitality Sensor accessory.