Game Design Sins.
We all know these. It's those little things that game developers don't seem to be able to get right - the little things that piss us off and ruin a game that might be perfectly awesome otherwise... but THAT ONE DIFFICULT PART OF THE GAME WITH A SAVEPOINT BEFORE A LONG UNSKIPPABLE CUTSCENE JUST MAKES YOUR BLOOD BOIL.
Those things! Those are what this list is about - things we want to see less of in future games!