The sale is for:

Chameleon Twist - (NUS-NCTJ-JPN)

Doraemon Nobita to 3 tsu Seireiseki - (NUS-NDRJ-JPN)

These games are Japan region but can be played on any N64 with the optional region-free kit available here.

The JP version of Chameleon Twist features significant changes/improvements including multiplayer power-ups being added to the main game, multiple instances of more complex level design in every world, and even an actual ending showing your escape from the Ghost Castle (the international versions jump right to the credits).