This is much like the NES coupler (see elsewhere on my store) which can play the same games, however the controllers are similar in some ways they still have a different shape and cabling considerations so I've created this unique and comfortable configuration for the Famicom lovers out there.  

The complete list of games so far that I know take advantage of this:

Smash TV

Spookatron (homebrew)

Crazy Climber

Silence Service (access to torpedo 3 and 4)

Gyromite (let R.O.B. take a rest)

This will also open up future homebrew games to leverage this device to allow more dual d-pad games to be created in the future.

Additionally if you rotate the controller 90 degrees clockwise, some owners have expressed they like like playing some games like Gradius in this setup where they use the fire buttons of the second controller as it creates a slightly more offset feel like some modern consoles.  

This coupler simply uses gentle friction to hold it comfortably in place.

NOTE: To insure there is no misunderstanding, this is for the coupler, the game controllers are not included. Thank you :)