 Battles in The Thousand-Year Door borrow elements from the original Paper Mario and Super Mario RPG. The turn-based system, in which players select an attack, defense, or item from a menu, is augmented by timed button presses that can result in substantial attack or defence bonuses when performed correctly. A similar "action command" was also used in all released Mario RPG games. In The Thousand-Year Door, each of Mario's party members now have their own heart points (HP) and may receive any attack that Mario can receive. When a partner's heart points are reduced to 0, the partner becomes inactive for the rest of that battle and later battles until recovery. If Mario's Heart Points are reduced to 0, however, the game ends. Flower Points — which are required for special moves — are shared among Mario and his party members. Defeating enemies awards various numbers of Star Points to Mario; for every 100 Star Points, Mario is able to level up. Mario can choose to upgrade his heart points (HP), flower points (FP), or his badge points (BP). The battles take place on a stage in front of an audience; if the player performs well in a battle, the audience can assist Mario by replenishing star power, throwing helpful items on-stage, or inflicting damage on the opponent. Conversely, the audience may throw damage-causing items at the player or leave if the player performs poorly in a battle. For every 10 levels, the stage will increase by fifty audience members for a total of 200 after level 30.
