* without using the grand list of CRPG clichés: http://project-apollo.net/text/rpg.html
I'll bring attention to the "shit our vehicle's stalled and there's enemies coming out of everywhere, shoot them all while I repair the vehicle!" cliché. Primarily in FPS games with an on-rail vehicle mission, I think there's at least one in every Call of Duty. Terribly overused and makes you wonder why the enemies were reserving all those soldiers for the off chance that the enemy vehicle stalls.
And similarly, the "get on that machinegun 'cause enemies are going to come out of every door in that little area!" cliché. Again, mostly in FPS games, I think there's at least one in every level of every Call of Duty game. And again, doesn't make sense why the enemy waits until they're outgunned to attack you.
So let's post awesome and awful videogame clichés.

Well, there's the classic adventure game cliché of "Aww, the bad guy caught you and locked you up. Now figure out a way to break free again".

Escort missions.
Oh what's that, you're unarmed? Then why don't you take one of my weapons? I have more than I should physically be able to carry anyway.

GRRRRRR main characters.

In EVERY space-sim type game you have to escort some freighter or convoy of freighters in the middle of a war zone. The only thing is that the contract for this was given to the company that had the slowest and most fragile ships around. If you are very lucky it might have some defensive weaponry but don't count on it.

When you kill the final boss and it transforms into a bigger monster.

Does this also exclude this list?
http://www.flyingomelette.com/oddities/rpgs.html

Don't cheat.
How about the "I'm a poor farm-boy in a safe villager. Oh not. Village is destroyed. I'll fight of the wave of invaders on my own with a stick. Wait, I'm the prophesised one? No, really? Sweet."?
Karl

A lot of those tropes are from JRPGs, could do with a distiction for western stuff.
"Hero from another world" tends to get used a lot, the entire Ultima series was based on that one.
The whole world revolves around what you do in the majority of RPGs (and games in general).
I'd love to see an RPG where you aren't the only adventurer around, and if you ignore a quest for too long, it will be done by other adventurers (that you'd hear about! and if you were evil, perhaps you could track them down... or they may find you...).
You could continue this in RTS games, where losing a map/sector wouldn't be game over, instead you would just cede that territory to the enemy, and would have to reclaim it later.
Thankfully FPS games are starting to move in this direction, I guess there were only so many reasons why you could be a lone soldier gunning down thousands of enemies by yourself.

lol, open world is used too often.
why must I always be in an open world where I can do anything? sure it's nice, but sometimes it detracts from the story.
like in oblivion, on your way to do the main quest, you're given so many opportunities to do something else, to play with some innane feature of the game, instead of actually getting to the main course of the game. Sometimes I don't want to do any of that minigame crap, just get to the goddamn point.
Fallout is an open world, Mass Effect is an open world, Oblivion, open world.
Sure, it's nice, and many of these games do it rather well, but must you always emulate it?

Yeah, it can detract from the urgency of the plot as well. Like in Mass Effect. We know where the bad guy is going so we better catch up so we can st- OH WAIT THERE MIGHT BE SOME SHINY ROCKS ON THAT PLANET OVER THERE!

Bad guys don't kill good guys, they just lock them up. Good guys have no remorse at all.

Where do I begin?
1. The main hero/heroine in any RPG (or any other game where you make your own character/have freedom of choice) almost never has any defined background. You almost always play a nobody from nowhere land.
2. Your guns are always more-or-less perfect. The sights are NEVER off, they ALWAYS hit in the general area of your targeting reticule/crosshair/ironsights, they NEVER require maintenance, and in extreme cases might not even need to be reloaded periodically.
3. Regardless of what your character is wearing, he/she is almost always more than capable of enduring more damage than common enemies.
4. Pretty much every FPS game includes some variety of:
A. A melee weapon, like a knife or baton
B. A pistol
C. A shotgun
D. A machine-gun.
E. Grenades
F. Grenade launcher (includes Rocket-propelled grenades)
5. Rocket-propelled grenades move a lot slower in a game than they do in real life. Sometimes the same goes for bullets.
6. Your character is almost always more accurate and adept with all weapons than any opponent is with any weapon.
7. No matter what game you're playing, there will almost always be a way to make things explode, because explosions are cool.

Certainly not limited to games but, having a car explode by shooting its petrol tank is ridiculously unlikely unless you are using incendiary rounds.