Rule Zero

In an open-ended tabletop RPG, game balance is sometimes hard to achieve, and, with an unlimited number of choices available to the players, a Game Breaker is inevitable (especially if you have a Rules Lawyer at your table). For this reason, most tabletop roleplaying games mention some version of Rule Zero: The Game Master is always right.

Rule Zero is simply a reminder to the players that the GM has to exercise some common sense and is permitted to supersede the rules when the rules would ruin enjoyment and fair play. While a GM has fiat to exercise Rule Zero at their table at will, they are reminded that excessive arbitrary use of this rule will eventually lead to an empty game table.

Can be worded very positively, as in "Rule Zero: if an interpretation of a rule is more fun, do that" or very negatively, as in "Rule Zero: don't give the GM ideas." How the rule is expressed is usually a good clue to the GM as to how far he can push it.

Sometimes the rule is expressed as:

Rule 1: The GM is always right.
Rule 2: If the GM is wrong, refer to rule 1.

"GM" is interchangeable with other authority figures.

Railroading is an example of excessive (ab)use of Rule Zero. Compare Because I Said So and Screw the Rules, I Make Them!, especially for other media.


  • The Trope Namer for Rule Zero is Dungeons & Dragons, the first tabletop roleplaying game. Many other games take it from there, but it's Older than You Think.
  • Mutants & Masterminds is notable for having a game mechanic for Rule Zero called "Gamemaster fiat". The Gamemaster is permitted to arbitrarily create setbacks to keep his story on track (such as having a hero slip and fall if he's about to catch the bad guy long before the adventure says he should) but requires that the Gamemaster award the hero a hero point (which players can spend later on to perform impressive feats normally beyond their abilities).
    • Players can go a step further with "complications" which are specific recurring dramatic setbacks that a GM can use on a player that fit the player's character concept. A common example is the secret identity.
  • OnlyWar directly specifies early in the general rules section that the Game Master should exercise common sense and discretion to make things work ideally and many rules refer to "Game Masters' Discretion" for things where any specific rule set would be impractical.
  • Paranoia is notable in that it's one of the few tabletop games in which arbitrary use of Rule Zero is encouraged. The GM is allowed to fudge rolls, to let other plays fudge their rolls or fudge each other's rolls, and generally discard the rules as long as Rule of Fun is observed. The justifying reason for this caveat? Any player who tried to call the GM out on it would be acknowledging they have read the rules, which are above their security clearance. note 
  • B.A. From Knights of the Dinner Table averts this. He plays every rule for better or for worse. He eventually seized control of his game through the use of a GMPC and his control over non mechanical story elements (even in the PC's backstories.)
    • To a degree, this is true of almost every GM in the Knights universe. A HackMaster GM is accredited by a national association before being allowed to run an "official" campaign. Years' worth of legal precedent have gone towards removing the concept of Rule Zero from accredited, tournament legal campaigns. After all, since tournaments usually involve opposing groups and characters competing against one another, it makes sense to ensure that they're all playing on the same page. This has evolved into the "Rules of Fair Play" doctrine, where all rules introduced into the campaign apply to both characters and NPCs without bias or discrimination, effectively removing a GM's judgment from the equation. This environment makes B.A., and other GMs, extremely creative umpires who arbitrate how invoked rules play out within their games.
    • Weird Pete is the opposite extreme enforcing Rule Zero through demerits that can result in level loss and can only be undone by working them off in his gameshop unpaid.
  • Averted in World of Synnibarr, which actually imposes limits on what the GM can and cannot do:
    "Fate [the GM] has absolute control during the game regarding rolls and interpretation of the rules. Fate may not, however, deviate from the rules as they are written, for if he or she does and the players find out, then the adventure can be declared null, and the characters must be restored to their original condition, as they were before the game began."
    "Players may attempt what is known as 'calling Fate.' This means that if a ruling is disputed by a player and he challenges Fate and is found to be absolutely correct, the player may receive double gaming points [XP] for the entire adventure."
  • Dane from Statless And Tactless agrees to give up rule zero in relation to a player to get him to bring a friend. It doesn't go well.
  • American Football has a few rules against "palpably unfair acts", which function as this (The NFL has Rule 12-3-3 for players and substitutes, and Rule 13-1-7 for non-players—see below for an example). They're not used very often, and when they are, it's usually an obvious case (such as a substitute running into the field from the sideline during a play and tackling the ball carrier), when the advantage gained by the offending team was so extreme that a lesser penalty would not be sufficient to mitigate it. In high school and college codes, it's even possible for the referees to declare the offending team to have forfeited.
    NFL Rule 12-3-3: A player or substitute shall not interfere with play by any act which is palpably unfair.
    Penalty: for a palpably unfair act: Offender may be disqualified. The Referee, after consulting his crew, enforces any such distance penalty as they consider equitable and irrespective of any other specified code penalty. The Referee may award a score.
  • Rule Zero is used often in games played by Mr Welch of Things Mr. Welch Is No Longer Allowed to Do in an RPG to protect the game from his more creative excesses. Usually, there is no rule stating he can't do what he wants to do. In general The Loonie is a Player Archetype that will often require the exercise of this rule to keep the game on track (though knowing when not to crush a Loonie's creativity with Rule Zero can be just as important).
  • This is one reason why Magic: The Gathering has Loads and Loads of Rules: all official tournament referees are allowed to invoke Rule Zero if there is no precedent for how certain cards interact. Their decision then gets stuck in the big ol' list of errata/clarifications.
  • In many sports, to prevent Rules Lawyers from abusing obscure loopholes, there's always a rule about how the officials/umpires/referees are the ultimate authority on the rules. One example is Major League Baseball, which has rule 9.01 (c), which states "Each umpire has authority to rule on any point not specifically covered in these rules".
    • This is prevalent in Mixed Martial Arts, still a very young sport that's trying to tweak rules as the years go by and fighters look to abuse looopholes in the Unified Rules, or clarify exactly what is legal/illegal. This is often left to the referee to make split second decisions during a fight based on their understanding of the rules:
      • Grabbing the fence is illegal, but pressing your hand against the fence is not. Where exactly the point is between grabbing it and your hand's natural curl is left up to the ref. Additionally, the rule was thought for years to only apply to hands/fingers, not feet/toes, and it was a common sight to see someone grabbing the fence with their feet. Recently, many referees have started cracking down on this practice too.
      • It's illegal to hit the back of the head, but what point is exactly the back of the head can vary depending on head types and the referee's discretion. The general rule is anything past the "headphone" area, but with people punching fast and people moving their head to avoid damage, the ref needs to make a judgment call on whether or not a blow went too far or whether it was an unavoidable accident, etc.
      • The three point rule for kicks/knees to the head has become a loophole abused by a controlled fighter to avoid being pummeled, putting down just the tip of a finger to the ground, making the blows illegal. Many refs are now letting kicks and knees go if the opponent is only skirting by on the rule by a technicality. Additionally, the ref has to make the decision in case of a hand going down while the kick/knee is in motion whether or not the blow was intentionally illegal.
      • The "12 to 6" downward elbow strike is illegal (due to ignorance when the rules were made, thinking this was some kind of killing power based on karate demonstration trickery), but any other variation is legal (i.e., "1 to 7" which is barely a degree off), and a ref will have to determine angle legality, along with moving heads and arms and whatnot, to determine if the movie was legal or not.
  • Most countries have laws against very vague crimes like "disturbing the public peace". They function the same as the other examples: when you're obviously doing something wrong without breaking any other laws, you're breaking these.
  • Panty Explosion Perfect averts this. The GM's role is very strictly defined and delimited. The GM can even have their own PC, with the only rule mod necessary to keep them from manipulating things in favor of their character being that someone else has to GM scenes where the GM's PC is the focus.
  • Rugby Union's laws has a long list of what is defined by "dangerous play and misconduct", one of which is that players must not commit "acts contrary to good sportsmanship".
  • Subverted with Munchkin, which has a Rule Zero, but that rule reads "Disputes should be settled by loud arguments among the players."
  • Played with in Arcanik. While Rule Zero still applies, players are capable of using the "Ingenuity System" in response to it. The system allows players to combine skills, attribute scores, and so on to create a ridiculously high skill roll that is almost guaranteed to succeed at whatever the problem is. The catch is that all of those numbers must be combined into a stupid plan that has no chance of working otherwise.