normal Team Fortress 2, it offers an environment with a much higher level of teamwork than in public servers. Most teams use voice chat to communicate, and use a combination of strategy, communication, and mechanical skill to win against other teams. Community-run competitive leagues also tend to feature restrictions such as item bans and class limits. These leagues are often supported by Valve via in-game medals (which are submitted via the Steam Workshop) and announcements on the official blog. In April 2015, Valve announced that a dedicated competitive mode would be added to Team Fortress 2, utilizing skill-based matchmaking; closed beta testing began in the following year. The competitive mode was added in the "Meet Your Match" update, released on July 7, 2016. Ranked matches are played six-vs-six, with players ranked in thirteen tiers based on win/losses and an assessment of their skills. Ranked matchmaking will balance players based on their tiers and rating. A similar matchmaking approach has been added for casual games for matches of 12-vs-12 players. In order to join competitive matchmaking, players must have associated their Steam account with the Steam Guard Mobile Authenticator, as well as having a Team Fortress 2 "premium account", which is unlocked by either having bought the game before it went free-to-play or by having made an in-game item purchase since. Formats Team Fortress 2 is played in a variety of different formats, which dictate the maximum size and composition of a team and can drastically change the impact of a single player's gameplay or choice of class. The two most basic formats consist of 12v12 and 6v6 ("Sixes"), the two being used on official Valve servers for casual and competitive modes respectively with no additional limitations. Most competitive leagues host Sixes but include limits on certain classes and weapons to preserve traditional, skill-based playstyles, for example limiting the allowed amount of medics or demomen to one on either team or banning certain movement-enhancing weapons from use. Other popular formats include "Highlander", a 9v9 format with a limit of one player per each of the nine classes, as well as a Sixes-inspired 7v7 variant thereof known as "Prolander" to allow for strategically switching classes during a competitive game. Characters and setting Team Fortress 2 features nine playable classes, evenly split and categorized into "Offense", "Defense", and "Support". Each class has strengths and weaknesses and must work with other classes to be