I hate it when a game has extremely obvious differences in quality as you play through it, being quite clearly the result of developmental trouble or simple lack of time.
Like Dragon Age Inquisition. The story missions are
awesome, but they're sparse and get drip-fed to you throughout the game while extremely padded by filler quests. When there are awesome bits of the game when you know they actually *tried* to make fun, but those bits are so few in between and you're stuck playing filler everywhere else. When you
know that the game could be better and you've
seen how good it can actually be, but it just doesn't reach there. It feels like the game's missed extreme amounts of potential.
And this is such a common thing, too. I first remember feeling this frustration with Hi-Rez's Global Agenda, that instanced PvE "MMO" game which has been dead for quite a while. The starting mission is awesome and cinematic and is just well-designed with an actual present story. But then the rest of the game is reduced to the standard MMO PvE structure. You do PvE raids and fight against AIs without any kind of comprehensible mission design or story elements or you do straightforward PvP.
This is the first mission (Sorry for the bad quality; first link I could find). Notice how it has an actual structure and gameplay.
This is standard PvE gameplay. Notice how it's just fighting through a map littered with hostile NPCs. This is the actual PvE gameplay.
I know that games like Global Agenda are clearly not focusing on story-based PvE, but it still frustrates me. The game could be as good as that opening mission, but it isn't, and it is extremely frustrating.
Also with (vanilla, at least) Destiny. The first mission of Destiny was actually pretty fun and atmospheric, but every other mission is just bog-standard "get to point then wave defense then mini-boss" with none of the atmosphere of the first mission. You know they had the ability to actually make fun missions filled with story and atmosphere, but they didn't! You get such sub-par content when you
know the developers are capable of doing something better!
It's present in so many games and I absolutely hate it. This may be my number one hated thing in the topic of games, even.