Tower Defense: Turrets Lite

This version of the game is lite (there are only the first 2 missions.)

The game belongs to the genre of Tower Defense.
Purpose of the game: retention onrushing enemy.
There are many types of turrets with different properties. Almost all of them have 10 levels (Flame Turret has 20 levels.)
You can change the priority for each of the turret (nearest,weakest or strongest target.)
In this game it is more beneficial to upgrade the constructed turrets as possible, than to build new ones.
To perform difficult missions, you need to have a good tactical and strategic abilities,
and the ability to make quick decisions and adapt to changing conditions.