Panel de Pon 64 was a cancelled 2000 Nintendo 64 port of the original Panel de Pon/Tetris Attack, which ended up becoming "Pokemon Puzzle League".
Sightings and information
When often bringing up Panel de Pon or Pokemon Puzzle League on boards, it was rumored that there was gonna be a planned Nintendo 64 remake of the original Super Nintendo Panel de Pon/Tetris Attack game 4-5 years later. It remains ambiguous whether or not it was the Japanese release of "Pokemon Puzzle League" or a tech demo that helped bring those elements into it. But was for some reason cancelled for unknown reasons, while "Pokemon Puzzle League" remained to be the only Panel de Pon game released for the Nintendo 64 that was never released outside of America.
A user stated that it's possible that the Nintendo 64 version of Panel de Pon was used in the Japan-only "Nintendo Puzzle Collection" for Nintendo GameCube, the Dr.Mario that was in the compilation was identical to "Dr. Mario 64" for the Nintendo 64 that was never released outside of America. Because of the lack of image evidence of the Nintendo 64 version, it's unknown if the cancelled Nintendo 64 version would have been different or same from the GameCube version.