F*** the rats.
You have cats.
Cats with guns . Command the cats and eliminate all the rats in the way.
Game icons from here : https://game-icons.net/

Controls :

Camera : Hold Right mouse button and move your mouse to look around.

Zoom: Scroll Wheel to zoom in and out.

Tower Interaction:

Click on a tower to open the upgrade menu.
Press E to upgrade tower.
Press Q to close menu.