Yeah, that always bugs me. If the freaking NPC’s are invincible why don’t THEY just go beat the game for you?! Or why do they even need saving if they’re invincible anyways?
You don’t fuck with Aria.
Mass Effect 2
When in doubt, Bash your way out (Left 4 Dead 2)
If you’re stuck on a military installation on the surface of mars and it’s Literally TEEMING with Demons from hell, you best Lock and Load (DOOM)
When the MARINES (not the national guard) arrive after a major catastrophe, they’re there to silence you, not save you.(Half-Life)
The door you want to unlock has a key that is behind another lock door whose key is… (you get the picture) Heretic series.
Nazis always seem to have an undead army hidden away somewhere. Castle Wolfenstein.
Can be applied to most rpgs.
If there is a monster within 700 yards of you, you will hear its obnoxious grunting constantly until you send it to its demise. (DooM)
Nazis were terrible at hiding their shit, and would often guard empty closets. (Wolfenstein 3D)
The elderly zoologist down the street always needs youths to go out and research animals for him. (Pokemon Series)
Should you ever move into a town populated entirely by animal-people, The local shopkeeper will own your house forever. (Animal Crossing)
Should the local Populace be suddenly stricken by a disease that turns them all into shambling cannibals, your best bet would be to avoid giants wielding Rocket Launchers and haul ass to the Local Waste treatment plant with a S.W.A.T. buddy in tow.(Resident Evil 3: Nemesis)
If it’s a Film, chances are the game based off it sucks[and vice-versa] (Movie games)
My left and right
you fail[a lot](Team Fortress 2)
Speedy thing goes in, speedy thing goes out.
Drinking 20 bottles of vodka gives you constant seizures. (STALKER : Shadow of Chernobyl)
that I must never, ever detatch myself from this railing. or I’ll Die! (Portal 2)
you can make things float with your mind by pushing “E”
Minigun will overheat when you shoot too long time, even it is designed for not to overheat.
Suicide= Epic fail (BFBC2)
Defit always can revive everyone when he die by head-shot.
Putting a mysterious needle in your veins doesn’t give you aids (BioShock)
to find the bad guys you must walk down one long straight road and eventually take a lift that will take you to him, fighting his henchmen along the way. (all streets of rage games)
Zombies are about as fragile as an expensive vase. (Left 4 Dead 2)
Old guns will jam about 3 days after purchase. (Far Cry 2 & Fallout 3)
If you slaughter their comrades without showing yourself or letting them find the bodies, guards will decide that it was “probably nothing”
~Thief series
“Is Garret really a master thief, or are the guards just completely retarded?”
Both 
“The more skin/body shape it reveals, the more effective female body armour becomes”
(virtually every PC and/or console game involving fighting female characters)
Also goes for most RPGs out there - even pen & paper type.