Polytope-form games and index/degree theories for extensive-form games

We develop index and degree theories for extensive form games allowing the identification of equilibria that are robust to payoff perturbations directly from the extensive form. Our approach is based on index and degree theories for games where the strategy sets are polytopes (and not necessarily simplices) and payoff functions are multiaffine. Polytope strategy sets arise naturally from topologically identifying equivalent mixed strategies of a normal form game.