I Know What You Did Last Summer: Game world is persistent between sessions and changes from one session affect game play on the following ones.
The Truth is Out There: Some external real world element, such as weather, time of the day, etc, affects gameplay. It MUST affect gameplay and can’t be only a scenario element.
No cheating (please): The game system relies on willing player participation to enforce the rules of the game world (e.g., hold your breath, close your eyes, etc.).
Approved for All Audiences: The game must not show any violence, not even cartoonish. Stepping on living mushrooms is off the list, as is killing any type of enemies, not even undead, though we know they’re already dead…