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.
I was coming to this thread to answer the same. New Vegas was probably my favorite game of all time, with it’s unique charm and creative blend of stories and character mechanics. I couldn’t make it past 5 or 6 hours of the FO4 (I really wanted to give it a chance), before I dropped it for good. Bethesda wanted to make an action shooter with a twist, and they did a good job of that, but it lacked the creative “it” factor that made me sink 600+ hours in NV across multiple playthroughs. Just talking about it makes me want to boot it back up right now!