This thread needs a revival, so without further ado
Irrelevant Side Quests
In which side quests, especially side quests that use mechanics not found in the rest of the game, have no impact on the rest of the game whatsoever. This especially applies to side quests which give you no ingame benefits except benefits towards completing the rest of the irrelevant side quests.
DWB Syndrome
In which guards, police, etc will target the player exclusively for law breaking, even minor law breaking, while completely ignoring any AI characters killing people, attacking the player, and so on.
Artificial Endgame Difficulty
In which the devs realize that their strategy game becomes too easy once you reach a certain point, so rather than balance things ingame to create reasonable challenges in late game, they simply either give the AI ludicrous bonuses for no reason or else utterly break/nullify a mechanic that the player may have been using. Shogun 2's Realm Divide mechanic functions a lot like this.
Patriotic Advertisement Games
In which you play as a ludicrously heroic American GI, fighting villainous foreigners (generic "Middle Eastern Terrorists" who hate America for no reason are default, but Russians or even the East Asian Villain of the Week will do in a pinch) with the help of superior weaponry, even in historical settings where the Americans lost. Why can I never play as the Viet Cong, or at least get two campaigns for one of the more modern games?!
Quick Time Combat
In which combat is overwhelmingly resolved by tapping a button at the right time, with this being repeated in nearly every fight in the game (see: Hitman Absolution). Or, even worse, in which combat is resolved in a pseudo-dynamic way by the player pushing the same few buttons repeatedly, guaranteeing a very flashy yet somehow unfulfilling kill (see: Assassin's Creed and sequels).