[Lalina204K]

https://www.romhacking.net/hacks/5238/

There's a neat hack for Super Mario Land 1 that makes it default to it's "second quest/hard mode" without having to already beat the game first, this comes in real handy and is much more convenient than having a separate save state dedicated to it. I'm curious if anyone has made something similar for the NES Super Mario 1, since that game has it's own "hard mode" where the goombas are replaced by Buzzy Beetles.

[Jorpho]

I would expect there's a Game Genie code to accomplish that, but five minutes of Googling does not reveal it (except for this thing for the GBA version).

Of course, you could always just use a save state, depending on how you are running the game.

[Dacicus]

Doesn't this hack accomplish what you want: https://www.romhacking.net/hacks/5354/ ?

[Lalina204K]

Doesn't this hack accomplish what you want: https://www.romhacking.net/hacks/5354/ ?

Tested it and that one did it, thanks for the link
Good to have one of these, I don't like reserving save states since those tend to get wiped when the emulator updates.