The original Fable. I wasn’t yet aware of Moleyneux’s reputation as a liar and bought into all the neat shit that was supposed to be in the game. Like at one point he said you could cut a tree and then adventure for years in game and the scar would still be there. Outrageous to think now, but he also said there would be a dragon fight and even back then this wasn’t difficult to make happen, yet it didn’t even have a dragon.
Also Oblivion. I had found Morrowind and fell in love, went back and got Arena and Daggerfall and loved those, too. They talked about all kinds of things it would have and showed graphics that looked top tier in magazines during development. It came out and didn’t look as good, was majorly dumbed down compared to Morrowind, and had even more technical issues. It was disappointing, but it still turned out to be a fun game regardless.