Total Defense 3D is a simple tower defense game with a vaguely futuristic campaign that takes place on four planets (maps differentiated only by the dominant color). The game has no real plot to speak of, instead prefacing each mission with generic filler text about tyrants or a resistance etc. Russian and English text is available, though the English translation is rough. The game includes a skill tree and gives the player three skill points to allocate after each mission. Skills allow players to boost the range, damage, and armor-piercing for the three basic tower types: kinetic, rocket, and laser. Skills also boost the abilities of radar towers and of the base itself. Maps for the game are small and sometimes allow the player to corner the enemy spawn point right from the beginning. Enemy units do not attack the player's fortifications but instead simply drive toward the base. Total Defense 3D features 22 missions (all with the same objective) and three difficulties levels.