Progressing up a level increases the hero's attributes and also allows the hero to gain new spell options (bringing role-playing video game elements to the series). Certain hero abilities can boost allied units. All heroes can equip items to increase skills, defense, and other abilities. In addition, Warcraft III adds powerful new units called heroes. For each enemy unit killed, a hero will gain experience points, which allow the hero to level-up to a maximum level of 10. For instance, units on a cliff have an attack bonus when attacking units at lower elevations. Creeps guard key areas such as gold mines or neutral buildings and, when killed, provide experience points, gold, and special items that can be used by heroes. Warcraft III also introduced a day/night cycle to the series. Besides having advantages or disadvantages for certain races, at night most creeps fall asleep, making nighttime scouting safer however, the line of sight for most units is also reduced. Additionally, some Night Elf units become invisible at night when not moving. Other minor changes to the gameplay were due to the 3D terrain. The game also introduces creeps, computer controlled units that are hostile to all players. Warcraft III features four playable factions: The Human Alliance - a coalition of humans, dwarves, and high elves - and the Orcish Horde - composed of orcs, trolls, and minotaur-inspired tauren - return from the previous games while the Undead Scourge and the Night Elves were added as two new factions. As in StarCraft, each race has a unique set of units, structures, technologies, and base-building methodology. If worker units have no jobs to do, their icons are displayed in the bottom left corner for easy assignment. The top left corner displays a portrait of the player's hero(es) for quick access. The game displays units and buildings as well as the environment from a classical top-down perspective with a slight angle that can only be zoomed and rotated slightly. The game features a fixed interface in the bottom of the screen that displays a mini-map, the information about the currently selected unit or group of units and possible actions for this unit or building. If multiple units are selected, the game automatically groups them by type, allowing all units of the same type to be given special commands (like using their skills). A small top bar displays the current time of day as well as the currently owned resources and the current upkeep level. Additionally, a new 'upkeep' system means that producing units over certain amounts will decrease the amount of gold one can earn, compelling players to focus on playing with a limited number of units to avoid penalties. The map is initially hidden from view and only becomes visible through exploration. Areas no longer in sight range of an allied unit or building are covered with the fog of war, meaning that while the terrain remains visible, changes such as enemy troop movements and building construction are not. During a game, players must establish settlements to gain resources, defend against others, and train units to explore the map and fight computer controlled foes. There are three main resources that are managed in Warcraft III: gold, lumber, and food. The first two are required to construct units and buildings, while food restricts the maximum number of units that can be possessed at the same time. Warcraft III takes place on a map of varying size, such as large plains and fields, with terrain features like rivers, mountains, seas, or cliffs.

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