Each Tower type can be upgraded during gameplay using scraps automatically collected from fallen enemies. A Tower can be upgraded in 1 of 2 different paths – one for range, one for power. Once an upgrade path is selected, the Tower can be upgraded 3 times!
A Hero gains experience for every enemy unit he kills. With this experience, the player can upgrade the Hero during gameplay in a range of areas – the Hero′s health, his weapon, armor, and his special Ability. When a Hero dies (sniff, sniff!), his experience is preserved in memory – so the next model starts with the same OS.