Lusory attitude is Bernard Suits’ term for the psychological disposition required to play a game: a player voluntarily accepts the rules and their arbitrary constraints (you may not use your hands in football) because doing so enables the activity they wish to engage in. Without the lusory attitude, the rules are mere obstacles to be circumvented; with it, the obstacles are the point (Suits via Bond 2014, see source-introduction-game-design-prototyping).
The concept explains why players accept friction that would be intolerable in any other context — and why cheating is a betrayal rather than just a strategy.
Related: game-definition, magic-circle, foundational-vocabulary, playtesting