In RPGs like Dungeons and Dragons, metagaming is when players use their knowledge of the game rules to get an advantage that contradicts how their characters might reasonably act. This is to some degree unavoidable, but excessive metagaming can also end up spoiling the role-playing aspect of the game.
Not only that, but metagamers can use their extensive rules knowledge to know the weaknesses of monsters they've never encountered before or build overpowered characters that don't make sense in the story. It's not quite cheating, but DMs should try and discourage it. Try these top tips for dealing with metagamers in your group.
10 Restrict The Books
This is something you can only do with a group of beginners but as with most things, the prevention is better than the cure. When you start a game with beginner players, make sure they only have access to the rulebooks that you are comfortable with.
The DM may even go as far as to make their own starting documents for players with only the information they want players to know. However, keep in mind that, whatever you restrict at the gaming table, D&D books are easily obtainable online, so you'll have to trust your group or resort to other methods.
9 Rule Zero
Not all RPGs are like this, but Dungeons and Dragons explicitly puts authority in the hands of the DM over the written rules. Also known as 'rule zero,' this means that the DM can run the game how they want, and this includes disallowing or banning character builds or items.
Simply put, if you find something in the rulebooks that you don't want in your game, feel free to disallow or change it to fit your campaign. It's best to plan this in advance; if you know a player wants something that you won't allow, be fair and let them know your reasons.
8 Just Say No, But...
If a player in your game wants to do something that only makes sense because of meta-gaming knowledge, a DM is within their rights to just say no. Yet, this can sometimes lead to some real-life personal conflict at the table, so always be prepared to make a counteroffer.
If a character can take an action, perhaps there is some way that they may be lucky enough to make the right choice based on their abilities, class or skills. Give the player a chance to explain their reasoning, and, if it makes sense, offer the chance of a wisdom check or other dice roll to have the 'character' figure it out.
7 Talk It Out
Say someone in your group is metagaming and it's becoming a problem. You don't want to change the rules or be heavy-handed. Sometimes the best approach is to have a straight talk with the problematic player.
Explain to them without judgment what metagaming is and how D&D isn't a competitive game, you don't have to leverage all the rules to 'win.' Instead, players have more fun when roleplaying their characters in a realistic way, and accepting that will make for a more rewarding game. Most people will come around, especially if they see examples of good play from others in the group.
6 Hide The Stats
This is an extreme way to play D&D but can make for very thrilling games. In this variant, important stats like hit points, saving throws and possibly even ability scores are kept a secret from players. The DM tells them whether they are feeling healthy, weak, or near-death and describes the attributes in general, not numeric terms.
Taking the numbers away from the players results in more 'realistic' roleplaying and especially tense combats, but the DM should be aware that this means a lot more admin falls on their already busy shoulders.
5 Change Your Setting
The standard D&D setting of the Forgotten Realms abounds with possibilities for adventure, but it's also well known and predictable for anyone who can get their hands on the core books or player forums. Monster weaknesses, characters, and conspiracies can all be figured out by players who do their reading.
More obscure settings that stray from the default D&D template, with lesser-known monsters, backstory, and special rules are harder to metagame. Many great settings don't even have 5E rulesets, but, with a bit of work, a DM can adapt them into a 5E game that rules lawyers can't exploit.
4 Change The Monsters
If changing the setting seems too daunting, consider tweaking the monsters to stop players reading the Monster Manual and using metagame knowledge in combat. This can be as simple as changing the damage values, swapping one weakness for another, or even just altering appearance so that it's not immediately recognized by manual readers.
Even better would be to create one's own monsters. The Dungeon Master's Guide has a workshop section just for this. Once you've created a few homebrew monsters, think about how they fit in the wider world and you're on your way to a unique setting!
3 Encourage Roleplaying
Players who become invested in portraying their character as a real personality are less inclined to metagame because they start to think in terms of how their character would act, rather than in terms of game systems.
To encourage immersive roleplaying, tempt your players with challenges that can't be solved with combat or a simple stat check or die roll, usually direct, non-violent interactions with NPCs work for this. You can play with incentives for this. Extra XP for roleplaying is nice, but less numeric rewards like gaining allies, prestige or information will discourage metagaming.
2 Forget Balance
The 5E Dungeon Master's Guide lists this example of metagame thinking: "The DM wouldn't throw such a powerful monster at us!" In this case, players are expecting the DM to precisely balance the game world for the characters as if it were a sport or videogame.
Don't do this. Add some verisimilitude to your game by populating it with challenges the characters can't always take on straight away. Don't 'throw' killer monsters at them—always give a chance for clever players to assess and avoid threats. The player characters are in a dangerous and uncertain world, and the players who realize this will act more like their characters would.
1 Embrace The Metagamer
Rather than struggle against the metagamer(s) in your group, it might be better to work with them. People get into D&D for all sorts of reasons, some love acting out their characters, some enjoy exploring the lore of the world, others find their joy in discovering the game systems and exploiting them. It doesn't make them bad.
Instead, try asking the metagamer what they like most about the game and direct that in a way that benefits your campaign. They can have the killer character build, item, or knowledge they want, but they'll need to do some roleplaying to justify it.