Always online requirement, even in games that are heavily multiplayer-oriented. Unless it's an MMO, requiring an internet connection is just DRM. The second I find out that a game I downloaded on iOS requires an internet connection, I immediately delete it. Like seriously, an online connection is required for a Bejeweled clone? Really??
Items/Pickups/Weapons having an obnoxious effect to indicate that they're something to pick up or interact with. A subtle effect like a glint or sparkle (a la Until Dawn or Fatal Frame) is totally cool with me. But things like giving an item a hideously thick glowy outline, or having a shine effect repeatedly run across it just looks totally out of place and is really annoying. A little bit more forgivable in games not about exploration, since the fun in those games isn't derived from the act of looking around and trying to find things yourself.
Rubber Banding. It doesn't increase the tension and excitement of the race, only annoyance.
Microtransactions in non-free games. Back in the day, we didn't have to pay for a couple bytes of game data to be manipulated in our favor, we had cheat codes. I honestly can't fathom how anyone can defend this abominable practice.
Cosmetic/minor DLC. Almost as pathetic as the microtransactions. At least you're getting new content for your money, but it's still just trying to milk customers by charging for something that cost the devs next to nothing to produce and could've easily been provided to loyal customers for free. I understand charging for substantial DLC, but stuff like charging $1-6 per DLC character costume in a full-price game? Pathetic.
Unskippable cutscenes. Okay great, the devs put too much time and effort into the cutscenes for them to be wasted... guess what? If people are playing your game for the story, they aren't skipping the cutscenes the first time through it. Robbing people of the ability to skip them is just going to annoy the piss out of players if they try to replay the game and don't necessarily want to sit through every single cutscene that they've already seen.