Personally there are a few games which left me very dissappointed, after hyping myself up for years in certain cases.
Divinity Original Sin: turns out I prefer more streamlined, less packed games (love Pillars of Eternity) and that coop play in a CRPG stresses me out.
Wasteland 2: I actually managed to finish this one but secretly I admit I was hoping for a better Fallout which I didn’t really get. New Vegas did the cowboy theme much better.
INSIDE: while the design was cool, it was just a ton of boring, easy puzzles in comparison to LIMBO, its predecessor.
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.
I was getting pretty sick of the chicken chaser bs until I was doing battle with town guards for shits and giggles. I parried an attack and the game loaded a different zone and auto-saved over my file. There was no way to go back because manual saving and loading were not a feature of the game. It completely ruined the whole thing and I never returned.
I liked Oblivion but I loved Morrowind. The ui and controls were substandard but the atmosphere and pacing of that game were amazing. Oblivion was Bethesda’s turn to mainstream and love for money.