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.