Angry Squares Defense, game for IOS

Defend your base from endless waves of enemies in this flash style defense game.
Simply tap an enemy to deal damage.
Survive waves to earn upgrades which can enhance both your offensive and defensive capabilities.
Deploy turrets for automated defenses and utilize four unique ammo types to hold off these relentless invaders.
The game gets progressively more difficult the longer you play as the enemy forces are constantly increasing in both health and numbers.
Compare your performance to the rest of the world with the online leaderboards.
Each round only takes about a minute to play and you can save your progress at any time.
How long can you hold out?