Money (bounty) is awarded for kills and interest is earned on the money left in the bank at the end of a level. Money can be used to upgrade the towers in various ways. To sell a selected tower, click the sell button, then confirm.
Current interest rate and bank balance are shown under the score in the top left of the screen. Current level and lives left are shown in the top right.
Select one of the initially empty 12 positions on your base in order to build a tower. The basic towers are as follows:
Rapid - Cheapest and inflict the least damage, but fast with a range advantage. Their rate of fire can be improved.
Chain - Average cost and range, but with high damage per hit. The damage continues to nearby enemies. The number of enemies affected can be improved.
Slower - Expensive and slow, but have the property of slowing 3 enemies to make them easier targets for other towers. Their slowing effect can be improved.
Pusher - Expensive, slow, with moderate damage. When an enemy is hit it is pushed a set distance out of its spiral formation. This distance can be improved.
Reaper - Expensive, very slow, but inflicts the most damage in a single hit. If this tower is the cause of an enemy's death, there is a chance that its life may be claimed and added to your own. This chance can be improved.
Gold - When this tower hits an enemy, the enemy becomes marked. If the enemy is killed whilst marked the bounty paid for the enemy is raised.
Each tower can have a separate strategy for which enemy to target. These are available at the bottom of the screen when a tower is selected:
Close - Target the enemy closest to the tower
Hard - Target the enemy with the most life
Weak - Target the enemy with the least life
Fast - Target the fastest enemies
Towers can be sold, but beware - you wont get as much for them as you invested in them!
A special enemy that releases a power is available every 2nd level (except where bonuses are available - see Bonuses). To use a collected power, select the corresponding power buton along the bottom of the play screen. Only one power may be active and will only last the duration of the current level.
SCR (Score) - The score from enemies is increased.
RNG (Range) - Tower range is increased.
MNY (Money) - The bounty from enemies is increased.
DAM (Damage) - Tower damage is increased.
FRZ (Freeze) - All enemies are frozen and move slowly.
BOM (Bomb) - All enemies explode!
A special enemy that releases a bonus is available every 8th level. The bonus is awarded automatically.
Reward - Receive a score and money bonus.
Interest - Interest rate is increased.
Lives - Gain extra lives.
Additionally, extra lives are awarded at 50,000 points, 100,000 points and every addition 100,000 points scored.