As in the game's predecessors, Team Fortress 2 players can choose to play as one of nine classes, each with their own unique strengths and weaknesses. Some class abilities have changed from the original Team Fortress, but the basic elements of each class have remained: the heavy class is slow, but has 300 health points, while the Scout class is quick, but has 125 health points. Only the Capture the Flag and Control Point game modes were available at launch.

There are also several features to enhance gameplay. Classes are designed to be balanced. Effective strategies result from using a variety of the different classes. Some classes work well together, such as soldier and demoman, or heavy and medic. Armor has been removed. Each class has a number of starting health points ranging from 125 lighter classes to 300 for more heavily armed classes.

Engineers can pick up deceased players' weapons to replenish their "metal" count, which is the engineer's building resource. Other classes can also pick up dropped weapons to replenish their ammunition supply. Ammunition is universal, in that a player does not need to find specific ammo types. Spawn rooms feature an equipment locker to fully restock ammo and health while standing in front of it, instead of the bags as in previous versions. Grenades have been removed from all classes, with the exception of the demoman's regular weapons.

The game includes detailed charts that can be changed to show two of the following while the game loads: time played as each class, average points, maximum points, most damage, and other class specific achievements. Persistent statistics tell the player how they are improving, for example telling them if they came close to their record number of kills with that class. The game only displays "points" to other players, instead of displaying each player's kills and deaths. The distinction encourages non-combat classes to stay out of combat: the Medic class will receive points for enemies killed by the player he or she is healing. Each player can see his own stats on the scoreboard.[citation needed] Players are able to spectate a game, including the option of spectating in first-person. A freeze-cam allows a player to see who killed them.

One can "dominate" a player by killing him 3 times in a row, then the dominated player can get a "revenge kill", leading to more points. Critical hit shots are chosen based on a player's momentum on the scoreboard, causing a player's rockets, bullets and grenades to become visibly coloured blue or red - depending which team the player is on - and to fire with an electrical charge sound. It is important to note that the sound means that a shot is critical, not a hit, so a player could miss a critical hit if he misses the shot. Melee weapons can also be critical hit charged. Critical hits can also be scored with a Headshot as the Sniper class. When you hit someone with a critical hit, a text icon appears over their head. Characters respond to the environment dynamically with dialogue, such as when on fire, when destroying enemy structures, when invulnerable, or at the start of the round. When one hits an enemy he will shout in pain, giving instant audio feedback.

In Capture the Flag mode, flags/intelligence dropped by the enemy team take 1-2 minutes to return to base, and display a timer over them. A friendly can't return the flag by touching it, as in other games, but the enemy can still take it from its new location. The defending team must hold the flag from being captured for 60 seconds. In Control Point mode, if a point is partially captured, it takes time to reset, giving the team time to get someone else there to finish the capture.

Team Fortress 2 features numerous "achievements" (similar to Xbox Live's Gamerscore) for carrying out certain tasks, such as scoring a certain number of kills or completing a round within a certain time. Messages appear in the bottom-right corner of the screen to inform the player of their success, or progress with regards to numerically-based achievements.

Map player limits are 24 on the PC (although it has been increased to 32 by the community), 16 on the Xbox 360 console and on the Playstation 3 console. Control point match maps also feature a timer after which the game enters sudden death, which is also timed, where no respawns are allowed in an effort to reduce tie games. If sudden death finishes without a definitive winner, a stalemate is announced. On control point maps, if the attacker controls any part of a point when time runs out, the game is extended to overtime. Overtime lasts until the point is completely lost or gained. If the point is gained, the attacking team wins or receives additional time if there are additional points left and the game is not already in sudden death.

Multiplayer modes include Xbox Live Player Match, Xbox Live Ranked Match, and System Link Match. The Xbox Live Player Match mode does not have statistics tracking and allows players to join matches already in progress or switch teams mid-match. The Xbox Live Ranked Match mode matches you with players around your skill level using Xbox's TrueskillTM ranking system. The System Link Match mode lets you wirelessly link two or more consoles for multiplayer matches. In all modes, only one person can play per console. A problem that has arisen with the game though, is that the match tends to have quite bag lag, if the host doesn't have a better than average connection. Luckily these bad games can be avoided by the ping meter shown (the more bars the better the connection), when searching for a game.