Where are the diamonds???

The game is fun in the beginning, but gets very difficult as you progress. It would be nice to use diamonds to boost the towers, but the only way to get them is to pay, which is messed up since this isnt a free game. There are tips before the level start that say you earn diamonds when you clear a level, but you dont. Im not sure why the dev doesnt fix this... I wont be buying another one of their games since they dont seem to care about the users.

Anti F-book about Tower Defense® HD