In single-player mode (commonly known as single player) the player will be alone to protect their core. In this mode you have to protect it against waves of enemies, which are predefined for each map (except in survival mode where mobs are random). Before each wave the player will enter the build phase in which they can build their maze, upgrade towers and upgrade their weapons. Once you end the build phase enemies will spawn and start walking towards the core.
When starting single player the only map available is Mine, with the others being locked. After beating the first map, the second map Bridge is unlocked. Once that map has been completed, the third map unlocked is Arc. The fourth map to be unlocked is Glade, the fifth is Complex and the sixth is Facility. If the player has any DLC maps, they can be played even if the previous maps aren't unlocked.
The difficulty will not change the types or numbers of the enemies, but they will adjust the amount of health the enemies have to make it harder or easier. In single player, there are four difficulty levels available:
|Creatures||Walker · Big Walker · Runner · Charger · Tank · Hoverer · Bobble Head · Soaker · Blocker · Spore Pod · Glider · Dodger · Spitter|
|Towers||Block · Televator · Lightning · Gatling · Scatter Laser · Anti-Air · Mortar · Slow Field · Amp Field · Holo · Killing Floor · Violator · Penetrator · Kairos · Accelerator · Drone|
|Weapons||Assault Gun · Freeze Gun · Sniper · Shotgun · REX · Tesla|
|Maps||Mine · Bridge · Arc · Glade · Complex · Facility · Aftermath · Aftershock · Cavern · Slums · Christmas · Yogscave · Corporation · Invasion · Chasm|
|Game modes||Single player · Multiplayer · Survival|
|Strategy||Level Maze Designs · Weak Spot|
|Insane difficulty guides||Mine · Arc|
|Storyline||Web Comic · Elysion One · The Old City · Brightsiders|
|Characters||Skye Autumn · Sweet Autumn · Jacksson Whalebrook|
|Miscellaneous||Achievements · Options · Coffee Stain Studios · Game Updates · Soundtrack|