Tetromino’s as a design implementation is not trademarked, but the concept and names are. The Tetris Company owns the rights to any use of Tetromono’s and Tetris in the gaming sector. Being said, the patents to such concepts have already expired, so unless they were using trademarks naming I think they are fully allowed to use it. I don’t know if the Tetris company has any legal standing here.
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Tetromino’s as a concept is not technically trademarked, but the concept and names are. The Tetris Company owns the rights to any use of Tetromono’s and Tetris in the gaming sector. Being said, the patents to such concepts have already expired, so unless they were using trademarks naming I think they are fully allowed to use it. I don’t know if the Tetris company has any legal standing here.