This lecture introduces the concept of game theory, focusing on modelling games, strategies, and general-sum games with multiple players. It covers elements of a game, formalization, representation, solution concepts, utility theory, and Nash equilibrium. The instructor explains how to compute Nash equilibria, Stackelberg games, and n-player games, emphasizing the importance of eliminating dominated actions. The lecture also discusses graphical games, implementing agents, cooperation, negotiation, and mechanism design in multi-agent systems.