Kingdom Rush is a tower-defense game that features a long campaign. A player must protect the country, including farmlands, forested areas, snow-covered regions, wastelands and the capital city, from more than 50 types of enemies and their evil forces across Easy, Normal, Casual and Vertical difficulty levels.
The player fights in each region by placing towers, archers, mages and ground troops in strategic locations marked with signs along straight, winding and split roads. They pay for the installations with coins. Every battle starts with only 100 coins, which means they must consider the battlefield and the best options for the terrain.
The player might place a tower with archers (arrows icon), defenders (shield icon), a mage (staff icon) or gunpowder bombs (bomb icon). During a battle, they can also place additional ground troops (sword icon) after the option recharges multiple times during each attack wave. They can also drop rechargeable firebombs (firebomb icon).
In Kingdom Rush, the player receives coins after killing so many enemies. They use the coins to perform tower and troop upgrades. The number of waves increase per battle. Additionally, they start over from scratch at the start of every level.
That said, the player can perform some upgrades that last from level to level. On a world map, they can select a hammer icon that displays upgrade options. They use star rewards to make changes to the towers and troops, including increasing attack damage and range, feeding and maintaining the health of soldiers and adding additional soldiers or firebombs to future battles. If they acquire gemstones, they can even pick new, amazing heroes.