Infamous:Second Son the game gets super repetitive from there. The beggining was great story wise.

Metal Gear Solid V

Agreed. I just finished it for the first time myself. The potential there is staggering, but it's mostly left unexplored. The last part of the game is especially disappointing.

@OP: for me, this is Metal Gear Solid 4: The Thread. The game started off wonderfully but by the time we get to act 5 the ratio of gameplay to cutscenes is ridiculously out of proportion.

I wrote this to brendude a couple weeks ago, to sum up my feelings on the game:

Act 1: love it

Act 2: love it

Act 3: this is a little weird, but, hey, I love it

Act 4: you're starting to lose me

Act 5: you lost me 

All mobile games

Bravely Default is the most recent I can think of

Well done xD

Original Release Diablo 3.

Was great fun until you beat it, then it just feels pointless until endgame /DLC coming out.

Phantom Pain. I would have perfectly satisfied if it ended at Chapter 1 then I saw Chapter 2 and thought "...really?". Still haven't touched it since. The repeating of mission was annoying too.

Uncharted 4.

The game was still amazing, and it started off so well and I was excited to see where the story would keep going, but the whole Scotland section where you're just doing a bunch of puzzles felt like it dragged on for so long and I was just hoping that would end and move on. It did pick up its steam again after though.

Doesn't happen very often, but the first Dead Space did lose a lot of my interest after the first hour or two. It just felt like the game played its best hand at the beginning and then never really recovered apart from a few high points here and there.

Pretty much every RPG ever haha.