It is a premium app, selling for £2.49 / $3.99 on Google Play.
Instead of automatically defending lanes, the towers in Tower Dwellers produce specialized combat units to send into battle.
The more soldiers your structures create, the bigger the army you have to defend against, and attack, the enemy.
Generating new types of units is as simple as setting up support buildings near the tower you want to upgrade, so you can focus instead on the game's real-time strategy elements of commanding units.
Tower Dwellers contains no in-app purchases. Buy it on Google Play now, and be sure to check out the new trailer below.