In late 1997 I had conquered Duke Nukem 3D. I wouldn't say I was tired of the game, but I could definitely use a break.
Also at this time, I started editing files that installed with games.
Personal favorite edits were replacing all the sounds in a German Monopoly ripoff with Simpsons and Beavis and Butthead sounds and replacing the taunts in Scorched Earth with very personal taunts aimed at my brothers.
So I started poking around my copy of Duke Nukem 3D. Most the files didn't mean anything to me, random DLL and map files. And then... then I found the holy grail.