Metagaming

What is metagaming?  Consider a boardgame like Chess.  The basic rules of the game are pretty simple.  Each piece on the board has its own set of movements, and the objective is to checkmate the opponent's king.  However, chess is much more complicated than its basics.  There are many different strategies to winning the game, and just as many strategies meant to counter those strategies, and then there's ways to adjust and balance out or beat that strategy.  To put it simply, the metagame is the game outside of the game which affects how an individual plays.

A metagame can present itself in different forms and ways depending on the type of game you're playing, and is actually very broad in what it can exactly entail.  I'll give three examples featuring TCGs, Tabletop RPGs, and MOBAs.

In a trading card game, the competitive metagame involves understanding which deck archetypes are popular in each competitive format.  For example, in the week following the release of the Theros set, the most competitive decks involved UW (and/or Esper) Control, Mono-Red Aggro, and GR Midrange.  In tournament play, these would be the most common decks.  Esper Control is defined by its use of five cards, so if someone is playing Blue, White, and possibly black you can expect them to have 3-4 of each of the following in their deck:  Azorius Charm (card draw and creature removal), Detention Sphere (card removal), Supreme Verdict (field wipe), Sphinx's Revelation (life gain and card draw), and Jace, Architect of Thought (card advantage).  As a finisher, it will more than likely have two Aetherlings (a very evasive and hard to remove creature), and as a control deck, it will have a variety of kill and counter spells.  Knowing this, the player can adjust their strategy and sideboard (a side deck of 15 cards they can switch cards in and out from their main deck between matches) before their next match, giving themselves an advantage because they knew what they were possibly against and had strategies prepared to go against it.

In a tabletop RPG, the players are set against the dungeon master and whatever their campaign can throw against them.  A player can choose to play as their character in-game would deal with the situation, but this can be disastrous if for example the character has no idea the statistical chances of surviving any instance would be or that staring at the snake-headed lady is likely to get you turned into a rock.  In contrast a player with the proper knowledge can make decisions like not getting in a staring contest with Medusa.  By taking information outside of whatever is going inside of the game, the player can survive and possibly outwit the dungeon master and accomplish any challenges that are presented.

As for MOBAs, like League of Legends, the metagame is defined by strategies that are used in the competitive scene.  The game has no defined rules as to who goes where, but the common strategy, and basic metagame, that is supported by the community, competitive scene, and developers relies on a solo champion in the top and middle lane, a ranged attacked damage carry (someone who can "carry" their team to victory late game) and a support champion paired at bottom lane, and a champion who can farm the jungle's neutral monsters while putting pressure on the entire map.  This is the basic format.  The metagame expands and changes from the basics between regions and even individual teams on the highest level of play.  For example, during the Season Two competitive scene, North American and European teams went for strategies that involved holding out on to the late-game and taking advantage of one or two champion that required a lot of time to get fully going, but once they hit a point were near unstoppable if protected and supported properly.  The Koreans and Chinese competitive scene, developed in a way that countered NA/EU strategies, and focused on tearing apart objectives and enemy champions early in the game.  The introduction of these strategies took competitive games from 40-50 minutes long down to 20-30 minute, sustain/defensive) supports (Soraka, Janna) began falling out of usage in favor of crowd control and damage supports (Lulu, Sona), and late game middle lane champions (Karthus, Anivia) fell out of favor for assassins (Ahri, Zed).  The Korean strategy is still the strongest in the competitive scene and NA/EU attempts to emulate have proved very successful in their own regions, but still come off as lacking against the originators of the Korean meta who continue to innovate and improve.