Page "Warcraft III: Reign of Chaos" Paragraph 4

The game also introduces creeps, computer controlled units that are hostile to all players.

Creeps guard key areas such as gold mines or neutral buildings and, when killed, provide experience points, gold, and special items to a player's hero.

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.

Other minor changes to the gameplay were due to the 3D terrain.

For instance, units on a cliff have an attack bonus when attacking units at lower elevations.