slightly more interesting was the Korean multigame carts with NES games showed here

and included in our list as super20m. Once found the menu bank

it was not so difficult to get the rest of bankswitch mechanism.

the interesting game is the 13th game, an "original" tetris clone (original in the sense that it's not a NES port)

A few NES games have glitches and there is no sound, so the work is not complete, but it's a promising start