I am not first to say, that it is running VERY SLOW. We all need a speed up button, to see results quickly! The waves are not slow, they are quick enought, but it's annoting to sit down waiting for results/for money.
Did you actually played more that five stages in both games? I'm a veteran TD player and sometimes I struggled on later levels so this game really doesn't need speed up button, due to it's difficulty. Unless you've figured out out the perfect strategy or view a guide, then it's a cake walk.
