Japanese publisher Arika, the company behind the Tetris: The Grand Master arcade series is also behind T4, an original entry in the Tetris series that features Xbox Live competitive play.
T4 gets the "four" in the title from the fact that Tetris Grand Master is on its third entry in the arcades with Tetris: The Grand Master 3 -- Terror Instinct. In addition to standard Tetris-style falling blocks play, the game features a "hold" button which allows you to hold a piece in reserve and switch it in for your current piece.
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