I would also like to know if this is possible, Binary.
Also, just as a quick aside, do you have any issues with 4 players on the Genesis? I ask, because I got multitap working on all the systems you mentioned, but on the Sega Genesis getting the multitap working seems to have made 2 player games not function properly (as in, any game that supports 2 players max no longer detects the second player). If I turn the multitap on player 2 off, then 2 player games go back to functioning properly. Have you encountered this issue? I’d love to have a way to leave multitap on without making 2 player games unplayable.
Anyway, back to the topic. If anyone knows how to get multitap working on the NES (or if it’s even possible) I’d love to hear from you. Frankly, if anyone has gotten multitap working on ANY systems other than the ones Binary mentioned, please let us know how you did it.
I’d really love to get multitap working on any and all systems/cores that support it.