My specific area of interest is designing the AI of real-time multiplayer games, for example, RTS games. Moves by players happen simultaneously, so I was wondering whether or not it would be modeled with a sequential (extensive form) game tree or something else. I don't know if this is even the correct approach at all, and if some other algorithms are more applicable.
How much of Artificial Intelligence design is based off of game trees or extensive-form games, and are there any suggested textbooks which thoroughly cover the subject game tree application to AI or AI of RTS games?