Wasn't Sega's version of Tetris (for both arcade and Mega Drive but not the U.S. version known as the Genesis) recalled after Nintendo won the rights to the license? I know Tengen's NES port and its parent company Atari's arcade coin-op version were, but wasn't the same said for Sega's versions?
If so, that might have been why Sega approached Jay Geertsen for the rights to his game called Columns, as that game is similar to Tetris. What do you think?
~Ben