I recently came across this post on the first Heroes of Might and Magic: As the poster had pointed out, there are major aspects of the Heroes game design that only made sense in H1. For its two vastly more popular sequels, the designers changed some parts of the game to be more appealing (replacing spell memorization with Spell Points and skills; making battlefields larger in each sequel), but didn't account for how they undermine pillars of the game. Similarly, I recall reading that some mechanics of the Total War series were made to fit the original Shogun: Total War. As soon as they made the first sequel, Medieval: Total War, Creative Assembly begun a history of adding new features without adjusting old ones. I think there was one game where the generals can gain experience, but their natural lifespan is too short for the experience to be useful, things like that. The series have never been properly balanced ever since. These are sequels developed by the original teams, who still managed to miss the point of their own design. Sequels made by different teams are worse. The best example is probably Dungeons & Dragons. The original D&D was inspired by pulp fantasy adventure novels; Gygax disliked LotR, and only added Tolkienesque player races at the behest of other players. The only source of Experience Points was treasure, because the player characters were supposed to be vagabonds and rascals who climb social ladders using the wealth they gained through plunder. They were morally grey as the inherent premise of the genre, and the system did not reward them for killing. Later versions shifted the vision towards both rewarding XP for killing enemies AND the more popular good vs. evil epic fantasy genre created in the wake of LotR. I don't think I need to stress the far-reaching harm this has done to the decades of pop culture influenced by D&D. What are your favorite examples of such changes, especially when most people have only played the sequels?