Call of Duty: Heroes have a similar gameplay with Clash of Clans. Players take controls an army of soldiers called Units and also called Heroes to help, to destroy enemy base. While Heroes can be controlled to an extent in that they can be moved, Units can't be controlled, except for the fact that the player can choose where to place their units. Also, Heroes get their own "Killstreaks" to use, such as the Predator Missile, Chopper Gunner, and EMP. Players also must build up their own base with defenses and structures so that it is protected from intruders. Gold and Oil are used to buy these things, as well as other things like a "shield" to protect the player's base for a certain amount of time, usually for a number of days. At the start of playing, the player automatically receives a shield for their base for free for several hours. However, shields expire automatically if a player plays a PvP match.