Play the World is the first official expansion for Sid Meier's Civilization III. It adds new cultures, units, and scenarios to the original game as well as several multiplayer modes. In Turnless mode, turns are taken simultaneously by each player and a turn ends when the turn timer runs out. In Simultaneous mode, turns are taken at the same time and when all players are done making their moves (or the optional turn clock runs out), the moves are made and units and buildings are produced. Classic mode is where each player takes their turn separately just like in the original Civilization III game.
There are also new victory conditions, most designed to speed up gameplay so multiplayer games do not last forever. In Regicide and Mass Regicide, players are given kings units which must be kept safe. If lose all kings are lost, their owning player is eliminated. In Elimination, a player loses if any of their cities falls. In Victory Control Points, players gain additional points by holding certain victory points on the map. In Save the Princess, there is a princess who must be rescued and held to gain points (sort of like capture the flag mode in other games).