Cheat Engine

[Bunny_Wabbit]

I watched a video once where some developers were reverse engineering Legend of Zelda for the NES, where they found the value that selects which dungeon you enter once you go through the door, and changed the code so that it takes you to the final dungeon no matter what dungeon you enter. What I'm asking is, because that value only changes for what I assume is a single frame, how would you find it in the first place? I'm sure in the video it was a matter of luck, but they weren't using Cheat Engine either so I'm wondering how you'd go about doing something like for this for any other game where not all the rooms are on a single map.

I found the X, Y and Z coordinates for the player position in Resident Evil last night, but it got me thinking that it's a bit useless as not all the rooms are loaded anyway.