Parasite Eve is an action role-playing game with many horror elements. Movement in the various environments is free. Movement in the "world map" (which is a map of Manhattan) is limited to specific destinations. Upon the player walking over a "hot spot," there's a chance of a random encounter. Each time the encounter occurs, the likelihood of the battle reoccurring decreases. Enemies materialize suddenly and though there is no shift to a separate battle screen, the player is bound within a perimeter of unseen barriers until the battle is over, either by defeating all enemies or using the Escape command.In battle, the game uses a pausable real-time combat system, much like Square's Vagrant Story (2000). In Parasite Eve, the player has an "Active Time Bar" (ATB) that sets the time for every turn to take action. While waiting for her turn, the player character Aya can be moved around to dodge enemy attacks. Upon each turn, the player may choose between attacking with their equipped weapon by pressing the attack button, using PE (Parasite Energy) for defense, assistance, or attack, using items, changing weapon or armor, or escaping the battle. If the player chooses to attack, the battle briefly pauses, and a dome/sphere symbolizing the range of the weapon appears,allowing the player to target an enemy within range. If the enemy is outside of the range, the shot is likely to fail. Even if the shot lands, the damage will be less than normal. When the player decides to use Parasite Energy, they must choose from the menu the desired PE skill. The same goes for weapon, armor or items; however, if the player should choose to escape, experience will be lost. Parasite Energy is slowly recharged over time.When not in battle, the player has the option of altering the weapon and armor attributes and effects with tools and super-tools.The player selects the "tune-up" option, choosing the weapon that will be altered and the weapon from which the attributes or effect will be taken. One of the principal RPG elements of the game is that experience-based levels are present. Each time the player's level increases, his/her attributes go up and BP (Bonus Points) are given. These points can be distributed to the ATB, item capacity, or attributes of a weapon or armor.