In late 2000s working as an IT-journo I explored a little bit map-making tool for Warcraft III (classic) - World Edit, and was awestruck with what a cornucopia of extra material the game actually had.
I mean, when you just play, you don't really take notice of the extra bits unless they are served you right in your face: early in campaign of either Reign of Chaos and The Frozen Throne you have to deal a little bit with non-player non-aligned units, scripted actions, etc., but later on it's mostly about managing standard units and structures while trying to eliminate those of the opposing force.
The abundance of the extra content, however, left the lasting impression that Warcraft III in its eventual 'factory' form was very far from exhausting its potential. That there was (is) much more under the hood than meets the eye.
This proved to be true in many aspects. The final campaign of TFT (Founding of Durotar) was, in fact, an RPG rolling the carpet for World of Warcraft. Then multiple modders provided tons of various campaigns (of random quality), including some that allowed, albeit with a lot of 'buts', playing melee games for the races beyond the preset four. Finally, there is a certain bunch of the materials hidden from the user access, and later recovered using a plethora of tools created by modders.
But it's not only Warcraft III that I'm actually blabbering about. There's the very same case with many other (old) games in fact - at least the moddable ones. Doom, Quake series, Bethesda's The Elder Scrolls and Fallout series, many, many others - moddable and convertible titles that often get refined and/or altered beyond imaginable, so the fun that they bring gets multipliedd manyfold.
Frankly, I think it's an art phenomenon, above anything else.
Would you share your opinions?