Seeing the videos, I don't think this was meant to be discovered since it seems the game is missing some sound effects and maybe animations of the ball. Well, I supposed since it's accessible by anyone on the right day it is a discoverable easter egg, but I don't think Nintendo intended for it to be really played seriously, which gives the idea that this is an omamori or a tribute more validity imo.
Really interesting that they seem to have added motion control to the game as well (although I haven't seen video of anyone trying it) and an overlay for how to do it (guess it's not technically an overlay since they just put it in the 4:3 aspect ratio sidebars), so it must be the original game since it needs to run on an emulator, but they also tweaked with parts of it as well? Possibly a test in retrofitting stuff like online play and motion controls to the original games?
Such a cool find.