1. SEWERS - I am sick and tired of trucking through a sewer because its the "secret" exit. Every boss must be stupid as hell to have not realized that by now. "Hey did you ever find out where that prisoner went?"
"Yeah he climbed through the 5-foot radius hole in the jail wall and went through the sewers. JUST LIKE EVERY OTHER GUY WE PUT IN THERE. Where the hell else would he have gone? Were you expecting him to try the door when there's that kind of opening?"
I don't want to wade through waste in my own life, so why would I want to watch someone do it virtually?

2. Cookie Cutting - The cold veteran space marine. The "funny" (quotes intentionally sarcastic) guy. Illusions Boss. God dammed sewer levels. Rats, goblins, spider, etc. cannon fodder. I have seen this shit so many times. Think more like Valve and follow Portal's example. They had an interesting idea that was unique, and the game was great. Now take a look at every RPG ever. They're all the same except, for the one or two races that are remotely original. At least trolls have some stylistic differences, but rats are rats. I am sick of killing rats. I'd rather try to kill a 7-foot-tall Steampunk Octopus-Shadow Demon Hybrid than another rat.

3. Jumping Puzzles - Or at least make the jump scheme like Legend of Zelda. You don't need to bunny hop constantly, it gets annoying (especially online). However, when you run off of a ledge you don't have to specify, "I don't want you to run off of the cliff and die. I'd prefer it if you would jump across the endless chasm." I hate jumping puzzles without this jump scheme that follow this logic.
Platform A and B are 9.995 meters apart, and between them lies and endless chasm.
Player 1 can jump 10 meters with a running start.
Player 1 can't grip the edge of either platform, due to a glaring incompitentcy in Developer A.
I've missed these jumps, and seen the character uselessly slide down past the gripable edge a thousand times.

4. Unskipable Movies - If I want plot I'll watch it. If I want to kick some ass, I want to skip it.

5. Lack of Multiplayer / Multiplayer Without an Online Option - I refuse to pay the same for a game that will get one play through as a game that I will rack up days of playtime online. A lot of games are great for the campaign and multiplayer wouldn't work out, but I don't want to pay $60 for a one play game.

6. Drab and Dull - Realistic games are doing a job in one department, graphics, but a lot aren't as fun as their stylistic neighbors. Games have the chance to be colorful and interesting, but less are using this option. Portal, Super Mario, Dragon Warrior, and Boom Boom Rocket are filled with color and are fun to play. I'm not looking for a rainbow to vomit on CoD4, but I like games that take on a style, be it steampunk, pop art, surrealism, etc.

7. Uniform - Samus, Bobba Fett, and Solid Snake are all easily identifiable by their unique uniform. This is cool for a story, but when everyone in a non-character based multiplayer looks exactly the same it gets annoying. Halo lets you do a little to your armor, but its enough to make me happy. A little customization goes a long way.

8. 1 crate = 1 clip - You can fit a lot of ammo into a foot locker.

9. One in Three - Games that exist merely as a bridge between a kick-ass start up and the epic final fight have a terrible track record. Try wrapping it up in two games or at least make the story like the first, when you weren't sure if there would be a sequel. Mid-trilogy games usually boil down to, "Yup were back and we've gotten bad-assier (I don't care if that word exists or not), but not quite enough to finish the story."

10. I am the wall - Beta test your games for longer than 30 seconds. Patches take forever to download and I hate seeing snipers that have become one with the scenery, literally.

11.  Bird watching - The camera should either be:
A) The character's sight, or
B) Over the shoulder and user controlled
It shouldn't be pinned against the rock wall looking through half of my character and focusing on the pretty scenery.

12. Airplane Effect - If I were attacked by a mob, would they let me fight them one-by-one and dance around me if I weren't locked onto them?

13.  20 Second War - Games have been getting easier lately. Remember a game called Contra that kicked your ass when you pressed the power button? Of course there was the Konami code, but a lot of people beat it with skill and only skill to show off. Recently, camping, bunny hopping, circle strafing, and a plethora of other "strategies" have reduced a major ammount of games from a skill based challenge to a complex multi-faceted game of Rock-Paper-Scissors.