My Version of "D&D's Unspoken Rules"

The Unspoken Rules of D&D

0. The Referee's Word is Law in the Game.

1. GM: RPGs are either shared stories about amazing heroes doing glorious deeds, or wargames in which bad luck can derail everything, and often does. It is statistically impossible for them to be both.

1a. GM: if playing Story Game then assume players have taken reasonable actions.

1b. GM: if playing Wargame then, Players, if you don't say it, it didn't happen and you didn't do it.

2. Players: Never split the party.

3. GM: The players will often break rule #2, unless you allow them to suffer the consequences.

4. Players: The statue is never just a statue.

5. GM: Avoid confronting characters with threats they cannot either defeat or avoid.

6. Players: "Are you sure you want to do that?" is code for "What you just said you are going to do, just might get your characters killed."

7. GM: Never plan to take the players’ freedom or stuff to support your plot.

8. GM: Better yet, don't have a plot, just have ideas of what could happen, and what the NPCs want to do, and let the chips fall where they may.

9. Players: If it was not previously written on your character sheet you do not possess it.

10. Players: Expect disaster and roll with the punches.

11. Players: The Dice Giveth & The Dice Taketh Away.

12. Players: The Party Will Be Misled and Deceived.

13. Players: Always watch your teammate’s back. Don't let anyone sneak up on them.

14. Anything said by the players in or out of character can and will be used.

15. Players: Thieves / Scouts should be in front leading the way.

16. A good Referee is not adversarial, a good Referee is impartial.

17. GM: All PCs should have a chance to shine.

18. Players: The golden rule is "Thou shalt not hog the spotlight."

19. Everything has consequences, somehow.

20. Players: Always as a priority, take out the opposing spell casters.

21. Players: Always check the bodies.

22. Players: There is no such thing as too much rope.

23. Timid players and over confident players are the two prime causes of TPKs; a party consisting of these two types will die.

24. Players: Missile weapon using characters should always have a melee weapon attack.

25. Players: Melee weapon characters should always have a missile weapon attack.

26. Players: Don't forget the options of negotiating, hiding, running, etc. Sometimes the one thing you don't want to do is fight.

27. Players: Pay close attention to descriptions.

28. Players: Make sure what you kill stays dead.

29. Players: Not all prisoners should be "rescued" and set free.

30. Players: Talk to NPCs to wheedle them for information and make useful friends.

31. Players: Don’t use offensive area of effect spells in close quarters.

32. Players: There is no such thing as an insignificant detail.

33. Players: Never push a button, pull a lever or its equivalent without knowing what it does.

34. Players: Never eat or drink something in a dungeon, unless you have first verified it is safe.

35. Players: Thou shalt not touch someone else’s dice without permission.

36. Players: Thou shalt not be a Rules Lawyer.

37. All player die rolls should be in the open.

38. Many, but not all, Referee die rolls should not be in the open if it will give players information that they have no way of knowing before they take the action.

39. In a face to face game, it is both expected and assumed that you bathe regularly.

40. Players: Unless you're actually IN a fishing village, any humanoid NPC found fishing is 99% likely to be something else in disguise, and often it will be a dragon.

41. Players: Nothing is ever THAT easy.

42. Players: Sea travel is never safe.

43. Players: The Referee runs the kind of game he would want to play in as a PC, and that's okay.

44. Players: Do not steal from or attack other PCs.

45. GM: Sometimes the monsters should be low on HP too.

46. Players: If you are playing in a home or anywhere snacks are brought and you are eating them, you should also be bringing them.

47. GM: Smart Play is inversely proportional to allowing PCs to suffer the consequences of Stupid Play.

Notes: 

The original list was gleaned from a Mewe post by Halenar Frosthelm Title: "From a thread (Oct 2022) over on my forum titled The Unspoken Rules of D&D".  All I did was fix a bit of logic, add a couple of nuances, and slightly organize it by pointing out who the rule is for.   Here for Players and GM's consideration alike.

Also, some people have questioned if this list is really specific to D&D, or RPGs in general.  That's a bit complicated to answer as RPGs really cover such a wide variety of games.  So I would say that this list is probably best suited for D&D and D&D-like games, Retro-Clones, and RPGs that are similar to D&D in design philosophy.