Counter-Strike is a first-person shooter in which players join either the terrorist or counter-terrorist team (or become a spectator). Each team attempts to complete their mission objective and/or eliminate the opposing team. Each round starts with the two teams spawning simultaneously, usually at opposite ends of the map from each other. 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 walk/move (a player can still take damage, having the player drop from a certain height during freeze time was the only way somebody could control the players starting "HP"). 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.