Castle Creeps TD gameplay is as per usual: enemies follow paths marked along each level, while you strategically place towers on designated lots. After defeating enemies you gain mana, which is used to build more towers. As you progress within your campaign, improving on each of your towers lets you create better, more powerful weapons.
Each type of tower is especially effective when played against a specific enemy type, so you have to learn to combine all the towers effectively to stop your enemies. Your hero, who is actually much stronger than any troop, can also potentially stop enemy advancement during most difficult situations.
Castle Creeps TD is an excellent 'tower defense' for Android with over 20 chapters in its single-player mode alone. In addition, you can also unlock twenty other towers and a handful of different heroes.