Team Fortress 2 is played competitively in various game modes ranging from 1vs1 to 9vs9, with many different intricacies such as class limits or team compositions, map pools and rulesets.
- 1 Main Gamemodes
- 2 Smaller Gamemodes
- 3 Competitive Formats without Seasoned Tournaments
- 4 Experimental and Exhibition Formats
These game modes are generally what players refer to as 'competitive TF2'; 'competitive players' typically participate in one of both game modes, but may or may not play the other minor game modes.
- Main article: 6v6
6v6, commonly referred to as 6s, is the most common competitive format, with the most skilled players competing with the most refined metagame amongst any other game mode. This format generally utilizes class limits of 2 on all classes save for Demo, Medic, Heavy, and Engineer, which have a class limit of 1 (this can vary depending on the league and ruleset of the league). 6v6 is mostly played on 5CP maps, as well as KOTH maps and usually features a team running two Scouts, two Soldiers, a Demoman and a Medic.
- Main article: Highlander
Highlander, also known as 9v9, is the next most popular competitive game mode. This format is played with class limits of 1 for all classes, with more lenient weapon bans than 6v6. Highlander is played on payload, KOTH, 5CP, and Attack/Defend maps. This format is generally accepted as the entry format to competitive TF2 as it has fewer entry barriers due to the format being closer to casual play in terms of classes, team size, and map pool.
While nearly all competitive TF2 players play either Highlander, 6s, or both, some also participate in the smaller game modes listed below. These game modes are less popular amongst the community but still have dedicated leagues that host regular seasoned tournaments.
- Main article: Prolander
Prolander is a 7v7 gamemode where each team has, at most, one of any particular class. The gamemode promotes prolific switching between classes as certain situations call for certain resources. Most commonly, a team will run one each of Scout, Soldier, Demoman, Medic, Sniper, and have two extra players switching between utility classes, rarely with Scout or Soldier replaced too. Currently, only RGL.gg supports the format.
- Main article: 4v4
4v4 is a competitive format featuring four players on each team, focused around KOTH and 5CP maps. Class limits are set to 1, with an additional restriction of 1 Heavy or Medic per team. Medics, Demomen and Scouts are commonly seen in this format, with Pyro and Soldier appearing quite often as well. Currently, only UGC supports this format.
- Main article: Ultiduo
Ultiduo is a competitive format consisting of two players on each team: a Soldier and a Medic. The objective is similar to King of the Hill, capture and defend the point from the opposing team. To win, you must run down the timer, which is done so by capturing the point. Since this gamemode consists of only a Soldier and Medic, it is heavily reliant on deathmatch skills. Currently, only UGC supports this format.
No Restriction 6v6
- Main article: No Restriction 6v6
No restriction 6v6 is an experimental competitive format featuring six players per team with no class limits or weapon bans. It is run by RGL and its debut season began on the 12th of March 2019 in North America. The format is designed to 'overthrow the meta' and (in the first season) teams were actively incentivised to use non-standard lineups. Maps are also highly varied, with 5CP, KOTH and Payload all being played. A common theme among the Invite teams was to run two Medics with a variety of other classes, but it is possible to use any combination of classes, for example, six Airstrike Soldiers or three Medics and three Demos, and the classes used would often shift significantly as a match progressed. The general idea behind the format was to start with a blank slate and see what new metas or tactics were established. This information could then be used to shape the format further, and/or be passed onto Valve for the development of their in-game competitive system.  The format expanded to Australia in the form of a one-day cup on the 18th of April 2020. 
Competitive Formats without Seasoned Tournaments
While these game modes do not feature regularly organised tournaments, they are still played frequently among some competitive players.
- Main article: BBall
BBall is often considered the "bar pool" of TF2, as many high and low level players across different leagues play it, and little infrastructure is needed to start games or tournaments in it. The game is played on a replication of a basketball court, with the intel being used as a ball. Players must use a combination of rocket jumping and DM to take the ball from their opponents, and jump into (on top of) their hoop while holding it. The ball initially spawns in the center of the court. When a side scores a point, the intel spawns near the opposite sides hoop, giving the team (to most recently lose a point) an advantage in the next play. The majority of weapons are banned in BBall, usually save for the Original, and in some cases the Escape Plan and Gunboats.
- Main article: MGEMod
One of the only established forms of 1v1 competition in TF2, MGE is a mod that offers players the chance to play 1v1 games where the first to a given number of frags (usually 20) is the winner. This format is more popular among Soldiers, Scouts and Demomen. It is used both as a common form of practice, and as a competitive format in and of itself. There are multiple populated MGE servers in all regions where players can practice their skills for use in various other competitive formats. Since May 2013, the MGE mod was updated to also support 2v2, which tries to simulate more of a 6v6 environment.
Experimental and Exhibition Formats
These formats have either been discontinued or exist in rare epithermal day cups or tournaments. They do not have any leagues supporting them and are not taken seriously by the majority of the community. Nevertheless, there have been tournaments played under this format in the past and are worth of mention.
A format popularised by the Kritzkast Lo-fi Offclass Cup, where a 6v6 format game is played, but with the Scout, Soldier & Demoman classes being banned from competition. (Video)
- Main article: Ultitrio
Ultitrio is a spinoff of Ultiduo that instead has three players on each team, these being a Soldier, a Medic, and the addition of a Scout. The extra class on each side results in a considerably more strategy-rich game format. There is currently no established competitive scene for Ultitrio.
Ready Steady Pan
- Main article: Ready Steady Pan
Ready Steady Pan (RSP) is an introductory derivative of 6v6. It is played like any normal match, with the players on each side using only the Frying Pan, among some secondary and jumper weapons for rollouts and movement. Heavies, Engineers, Medics, and Spies are disallowed in this game format.
- Main article: KnightComp
KnightComp is a derivative of 6v6. It is played just like normal 6v6, but the class limits and weapon bans are very different. Demoman has no class limit and Demoman players are not allowed to use any form of Stickybomb-type weapon. Medic and Soldier are both allowed at a maximum of 1 each. All other classes are disallowed in this format. This results in each team running at least 4 Demomen, either Full Demoknights or Hybrid Demoknights. The KnightComp League aims to be the permanent home of competitive Demoknight.
- Main article: National Heavy Boxing League
Heavy Boxing is a 1v1 TF2 e-sport where two Heavies melee each other in a ring until one is killed. There are various melee weapons and formats used across the community for Heavy Boxing. The National Heavy Boxing League is the highest level of this e-sport.