2. Unskippable Tutorials
Games like Assassin's Creed automatically assume that with every new game, you can't have possibly played any of the others, hence you being thrown headlong into a series of unskippable tutorial sequences that just leave most players crestfallen and irritable from the opening gambit. How hard is it to give players a prompt that says "Press A to skip tutorial"? Crysis 3 managed it; why can't all other games? Though it serves an obvious function, and these things generally only last a few minutes, they're precious minutes that I'd rather spend actually playing the game. The Metal Gear Solid franchise has it best, by asking you questions at the start of most of the games which then determine your gameplay experience.