Interesting thing i noticed about my Famicom EXT controller adapter and games

[YoshiFan501]

I noticed that playing through my famicom games, my NES games, and my ED FC, some games do not want to use the ext port as player one.

Super Mario USA for example, does not want to use the EXT port as controller 1.

Some American games, like SMB/Duck Hunt, do. but others, like Space Shuttle Project, don't

i thought it was a universal catch all, or like an override of player 1.

[zmaster18]

Yeah I popped in Super Mario USA the other day and noticed it doesn't use the extension controller. Same with Pinball and Arkanoid. I also noticed that Super Mario Bros 3 randomly 'acts out' with an extension controller as well.

[UglyJoe]

i thought it was a universal catch all, or like an override of player 1.

Nope.  It's entirely up to the game's software to decide if/how to use the controller(s) in the expansion port.

[P]

Most games do work though (especially Japanese-made games) which is why releasing external controllers was possible in the first place. Homebrew often doesn't work since they are often made by NES people who are not aware about it (something that seems to be changing though, as people are more aware of it now).

There's a list of some games that was discovered not to read the expansion port controllers here: http://www.famicomworld.com/forum/index.php?topic=6701.msg167005#msg167005.