Shoot on site!
Towers/trees/birds shoot instantly when mob enters their range (like a preloaded attack)
This impacts a bit the early game but it makes the game more fluid
Towers cost multiplier increases by 0.5 after 5/10/15 constructed towers
Map selection screen, added buttons to change Maps difficulty to max/min possible values:

Added number of paths & path lengths into Difficulty calculation (more paths = more difficult, the longer the path = less difficult)
Small text corrections
Small corrections