TowerDefenseToolKit (TDTK) is a an easy to use and flexible Unity game engine coding framework designed for construction of TowerDefense(TD) game. The aim of the toolkit is to allow as many variant of TD game as possible, with maximum flexibility to individual level design. It's designed with integration of custom asset in mind. Finally the toolkit is written with non-coder in mind so no coding skill is required to use it.
Here's a quick...
TowerDefense ToolKit 4