Levels

When a creature killed several enemies, it can gain level up ang upgrade its health and energy max values. New level changes creature's look. New level refills health and energy to max values.

Bear level 1:

Bear level 2:

Bear level 3:

Global constants:

    * // Contains max lives for each creature's level
    creatureMaxLives = [100.0, 150.0, 250.0] 
    * // Contains max energy for each creature's level
    creatureMaxEnergy = [100.0, 150.0, 250.0]
    * // Contains bullets capacity for each creature's level
    creatureMaxBullets = [3, 4, 5]