There's also the significant factor of input and display lag screwing up the timing, contributing to the perceived difficulty nowadays. Playing on real 6502 ha

There's also the significant factor of input and display lag screwing up the timing, contributing to the perceived difficulty nowadays. Playing on real 6502 hardware with a CRT, you get instant response, 17 ms at most. But play on an emulator on any modern OS on most any modern "smart" TV, and all those layers of abstraction often add up to an unplayable 100 to 200 ms. I've shown several people the difference between Zelda II on a PC emulator versus a real NES and CRT, and they all agree the real thing feels immeasurably sharper. Even Nintendo's own Switch console has noticeable lag to me. It's less of a problem for Game Boy games, since their feel is more accommodating of lag in the first place, thanks to the slow response of the original LCD.