Counter-Strike is a first-person shooter game in which players join either the terrorist team, the counter-terrorist team, or become spectators. Each team attempts to complete their mission objective and/or eliminate the opposing team. Each round starts with the two teams spawning simultaneously. All players have only one life by default and start with a pistol as well as a knife.

The objectives vary depending on the type of map, and these are the most usual ones:

Bomb defusal: The terrorists must carry a bomb, plant it on one of the designated spots and protect it from being disarmed by the counter-terrorists before it explodes to win. The counter-terrorists win if the time runs out with no conclusion.
Hostage rescue: The counter-terrorists must rescue a group of hostages held by the terrorists to win. The terrorists win if the time runs out with no conclusion.
Assassination: One of the counter-terrorists is chosen to act as a VIP and the team must escort this player to a designated spot on the map to win the game. The terrorists win if the VIP is killed or if the time runs out with no conclusion.
A player can choose to play as one of eight different default character models (four for each side, although Counter-Strike: Condition Zero added two extra models, bringing the total to ten). Players are generally given a few seconds before the round begins (known as "freeze time") to prepare and buy equipment, during which they cannot attack or move. They can return to the buy area within a set amount of time to buy more equipment (some custom maps included neutral "buy zones" that could be used by both teams). Once the round has ended, surviving players retain their equipment for use in the next round; players who were killed begin the next round with the basic default starting equipment.

Standard monetary bonuses are awarded for winning a round, losing a round, killing an enemy, being the first to instruct a hostage to follow, rescuing a hostage, planting the bomb (Terrorist) or defusing the bomb (Counter-Terrorist).

The scoreboard displays team scores in addition to statistics for each player: name, kills, deaths, and ping (in milliseconds). The scoreboard also indicates whether a player is dead, carrying the bomb (on bomb maps), or is the VIP (on assassination maps), although information on players on the opposing team is hidden from a player until his/her death, as this information can be important.

Killed players become "spectators" for the duration of the round; they cannot change their names before their next spawn, text chat cannot be sent to or received from live players, and voice chat can only be received from live players and not sent to them. Spectators are generally able to watch the rest of the round from multiple selectable views, although some servers disable some of these views to prevent dead players from relaying information about living players to their teammates through alternative media (most notably voice in the case of Internet cafes and Voice over IP programs such as TeamSpeak or Ventrilo). This form of cheating is known as "ghosting."