Board Thread:Questions and Answers/@comment-31440537-20170303223730/@comment-27701762-20170303231244

By "change" do you mean after you've already named the fallen human by altering the game files? That answer is no. The game doesn't register you as starting Hard Mode unless you enter "Frisk" as the name at the initial name selection screen. It appears to be the case that the game then constantly checks your name to determine whether you are still in Hard Mode or not, as you can change the name to deactivate/reactivate Hard Mode. I haven't checked what happens if you activate Hard Mode, then deactivate it, then complete the Ruins and attempt to reactivate it, but I would presume that either Hard Mode doesn't reactivate, or else the game fades to black as when you try to edit your location while in Hard Mode.