...now I just need to hunt down one of this cartridge. I've even got a Power-Joy to play it with. (Although any famiclone should work, or an NES if I got a Famicom>NES adapter.) Got the Power Joy used with no cart for $5, but it has 10 games onboard, including a rather decent Tetris clone, albeit with nonstandard tetrominos. At least they were square-based tetrominos, not like the ones in that unlicensed NES game "Pyramid" by Sachen. [Pyramid screenshot]
I wonder how many different Power Joy cartridges there are, anyways? Might be interesting to try to get "the whole set", as it were...