despite killing everything or everyone you've ever met, you'll still have to do what the city guard says.
Even when your sword can cut through a dragon in a single blow, you'll still need to find a key to get through that flimsy wooden door.
Anyone with more than two dialogue options is a love intrest
even though they were carrying them, guards never actually drink the health potions they have with them.
no matter how often you change clips, you'll never have to actually load any bullets into a magazine or sort through all the half spent ones you've ejected to find a full one. there are only 4 calibres of bullet in the world: pistol/smg, rifle, sniper rifle and shotgun shell. all the armies of the world adhere to these strict classes and make all their weapons interchangable.
in fantasy games no one minds sleeping outside, although nowadays thats called being homeless - and we all know how cold and sucky that is.
no equipment will clatter, or fall out, get tangled up if you attempt some stupid acrobatics. anyone who has done any re-enactment/larp will know just climbing over a fallen tree will instantly cause all your arrows to leap out of your quiver and on to the ground just where you need to put your feet. No equipment will rust, float away, go soggy, or rot no matter how often you go swimming. On a similar note cloaks and robes, and long coats are a ***** to fight in. a simple bramble bush would defeat most people in a cloak. oh yeah, and in games you can swim in a cloak, and not just drown.
a chest high wall is impervious to all harm and is utterly unclimbable. in a game no-one ever just brings a rope.
in games, any problem is either utterly insurmountable or capable of being solved by going to far away places and doing stupid shit for random people.
if there's a perfectly good postal service, why have i got to go all the way there to hand in some crap, ask advice, receive my reward etc.
no matter that an earth-like planet might have a land surface of 150,000,000 km2 (earth does) you'll always land right next to the quest start, find a person/object from orbit, and find it only has a maximum of 8 shops no matter how many people live there.
Lastly, no matter how weak and pitiful an NPC is, you can never just kill them and take the reward they offered you instead of doing their innane bloody quest.