1. Something bad happening behind glass
So I was playing Deus Ex: Human Revolution for the first time and I realized something while watching someone get smashed up against a window of glass. A lot of developers like to use glass as a barrier between you and something happening so you can stay in the game while not actually messing with the scene. I've seen this in a lot of games, like Deadspace, and Bioshock, and I'm sure it's been in plenty of games prior, but now I don't even find them entertaining anymore and when I see them I immediately think, "Well, they don't want me in there so I just have to sit and watch."
2. Moral "Choices"
It seems that almost every game that comes out now has some sort of morality system, making me decide to let somebody live or blow their brains out, but for some games, I don't want to decide, I just want to play. The thing I don't like about all the choices that you have in the game, is that when they make a sequel, your choice wasn't the "true" ending. Well gee thanks developer, now you make me feel like all of my work up to this point is worthless.
3. Bloody Eyeball Regenerating Health
You know what I'm talking about. Lift your head from cover for a few seconds and let the sweat warmth of lead seep into your body to see the amazingness that is the low health indicator. The screen goes grey and red, blood is splattered all over as if your player is wearing goggles soaked with it, your ears are ringing, and your heart is beating so loud it can be heard 10 miles away. IMMERSIVE YET?! Well if not, just wait 5 seconds and you'll be cured instantly from your blood loss.
4. All Sentient Aliens Are Humanoid
Almost any sci-fi game that features aliens showcase them being barely different from humans. They're an alien race evolved on a completely different planet, and depending on the environment they evolved in, they could be something quite weird and ugly. Yet, all you see are humans with blue skin and maybe even a little bit of a wrinkled forehead. Get imaginative, people. Don't be afraid to get weird with it.
5. Barrel = Boom
6. Shotguns Useless If Target Is More Than Four Feet Away
Who started this? Is it because of game balance or did somebody actually think that is how shotguns work? Because it isn't. So stop it.