I'm currently researching the evolution of game balance in video games, and I'm particularly interested in the "hidden" mechanics that developers employ to maintain a fair and engaging experience. I've seen many modern games use techniques like rubber-banding, dynamic difficulty adjustment, spawn control, health scaling, loot drop adjustments, catch-up experience, and more, but these sophisticated techniques must have had some origin point.
Can anyone provide information on the first known video game to employ some form of hidden balancing mechanic, whether in offline single-player or competitive online multiplayer scenarios?