Td Tower Defense is a fun tower defense shooter where the object of the game is to last as long as possible.

Each Level has a starting cash limit which you need to use wisely to build your towers to defeat each wave of enemies.
Each Level has a max wave total to show you how many waves are left.
These enemies increase in speed and damage resistance so careful planning is needed.

Enemies: Troop, Drone, Robot, Ship
Each enemy can only be destroyed with certain turrets.

Turrets: Air, Ground, Fire, Energy
Each turret can only destroy certain enemies and only the Fire Turret cannot be upgraded with the range add on.
Energy Turret can only be bought once you have an instance of the other 3 turrets.

Each enemy you destroy gives you more money to spend on more turrets and/or add ons.