Neltris

Neltris is a version of Tetris where, as always, the player must arrange falling blocks into lines, upon which the completed lines disappear. The twist to this version is that, when a line is completed, the screen is duplicated. The player continues to control blocks as they fall, but now their commands control pieces on both boards, which are usually not the same piece. The pieces continue to fall at the same rate, but the boards start to diverge with every new piece dropped. As new lines are completed, the board duplicates again.