Grand Theft Auto 3's Ghost City was my first proper experience of community discovery.
I was too young to fully appreciate game-breaking in the likes of Super Mario and Alex Kidd, so the idea of flying the clipped-wing Dodo aircraft from the runway of Frances International Airport at a very specific angle in order to break the 3D map and wind up in an otherwise inaccessible area—the section which housed the game's opening bank robbery cutscene, floating well beyond the playable map—blew my teenage mind.