The player starts with 20 lives, and has to withstand a number of enemy waves based on the level. When the level is completed, stars will be awarded depending on the number of lives left:
- 18+ lives: 3 stars
- 6-17 lives: 2 stars
- 1-5 lives: 1 star
The main storyline consists of 12 (Kingdom Rush) or 15 (Kingdom Rush: Frontiers and Kingdom Rush: Origins) levels. Only the first levels (Southport, Hammerhold and Gray Ravens) are initially available; the other levels must be unlocked one by one by finishing the previous level. When the final level of the main campaign (The Dark Tower, Emberspike Depths and Shrine of Elynie) is beaten, the Elite levels become accessible (some of which are not available on every game platform). Elite levels might be independent (unlocked immediately after the final level is beaten) or organised into mini-campaigns (must be unlocked one by one like the main campaign):
- Independent: Sarelgaz's Lair, Ruins of Acaroth, Rotten Forest, Fungal Forest, Darklight Depths
- Rise of the Bandits: Hushwood, Bandit's Lair
- Winter Storm: Glacial Heights, Ha'Kraj Plateau
- Burning Torment: Pit of Fire, Pandaemonium
- Rising Tides: Port Tortuga, Storm Atoll, The Sunken Citadel
- Shadowmoon: Bonesburg, Desecrated Grove, Dusk Chateau
- The Curse of Castle Blackburn: Rotwick, Ancient Necropolis, Nightfang Swale, Castle Blackburn
- Hulking Rage: Galadrian's Wall, Blood Quarry, Beheader's Seat
- Bittering Rancor: Duskwood Outpost, Duredhel Outskirts
- Forgotten Treasures: Dwaraman Gates, Tainted Pit
GREAT DEFENDER Complete all Campaign stages in Normal difficulty.
SUPREME DEFENDER Complete the campaign in Hard/Veteran difficulty.
GREAT DEFENDER Complete the Campaign on Normal difficulty.
SUPREME DEFENDER Complete the Campaign on Veteran difficulty.