The Reality Clause*
Do I really need to explain this again? Well, since some may not know it, i will.
You must play realistically. Thus, if you think your character needs something extra, you must have put it on the original character sheet. If it is not there, then it is not in your inventory. If you want a power, it must be on your original character sheet. If it is not on there, then you don't know it.
You may find items by looting corpses, trying to pickpocket someone, buying it, or if i say you notice it. You may only obtain new powers when I say you do. Thus, if you want to carry a beef jerky supply, but didn't put it on your character sheet, then you have to obtain it; you can't just poof it into your inventory. If you want to be able to sniff out magical crystals, you have to request that as a power upgrade. However, this example (sniffing out magical crystals) is impossible and will not be granted.
Now please, when you make an action, you must attempt it. You cannot say, “I smell the corpses,” unless I have stated that you can smell them. You cannot assume that there is a pot nearby; you must look around for an object to bash the NPC or monster over the head with, and I will tell you what is available for the action.
It is my job as the GM to describe the setting, NPCs, and events to you. You as the players may interact only with what is defined by me. You may not define anything other than the personality and attempted actions of your character. But that means that their inventory is set in stone until something occurs that causes you to interact with its contents.
To summarize: you attempt, I say succeed/fail; your items are pre-defined; the world is defined by me, and you cannot add any details to it.
This is the Reality Clause. This is real for your characters; this is not a game to them. Thus, you can't possess the infamous i-am-invincible-and-can-do-whatever power; you possess that which you are defined as having. You are not this world's creator; I am. You are just people living in my world.
I hope this is clear and not challenged.
Thank you all.
(*=
Majority of The Reality Clause was borrowed from Silver Tsumugari and her Rebirth roleplay, and then slightly edited by me.)