He is talking about games with the classic gameplay pal, otherwise that would be the first on my list too, if you play it in Hard Mode.
It's also worth noting when talking about these things that in some cases games were significantly harder in the English localization than the original Japanese release to discourage people just renting the games instead of buying them. (While iirc the Japanese market didn't have to worry about this because renting games is/was illegal there.) This was a common practice in the 80s and 90s and resulted in crazyhard game changes like the original US release of Resident Evil not having auto-aim(!!) but in the Castlevania series mainly manifested itself in regular enemies doing more damage in the later stages I think.
I haven't beaten Castlevania 3 yet due to one of these changes. Unlike the Japanese original you start at the beginning of the final stage instead of at Dracula when you continue in the English version. (You start halfway through the stage when you lose a regular life to Dracula.) Not that the final stage is very hard or long once you get used to it/know where the power-ups are, quite the opposite actually, it's just annoying and time consuming having to make your way all the way back to Drac for a few seconds of practice against him until he kills you.
You have sure? I think Auto-aim doesnt existed in RE1, they introducedd it in Director's Cut (that isnt the same as RE1 JP version
). Also CV is one of the only franchises that are harder in US than in JP that I can remember right now, can you say some others please? I want a excuse to return playing games. xD
I remember that Megaman 2 have a easier mode option only in US and SMB2 doesnt even have been released in US because of being "too difficult to the occident".