The term "base game" refers to the basic play mode of a slot before any extra bonuses or special features are activated. It includes the regular symbols and payouts found in the game as well as the rules for winning combinations and the number of win lines. A base game serves as the basis for all other functions of the game and determines the specific house edge of the machine. It is the heart of the game and forms the basis for all the fun a player is going to have!