my starting order day 1) pet shop slot 3, newsstands slot 2 & 3. This should get you $2000 bonus which equal to 2 free newsstand. then basically you buy every shop except restaurant when you have the money and add a newsstand next to it. I build in this slot order 3, 5, 7, 8 then random.
beaten level 16 and badge didn't come. strategy: I make sure that my angel attacks slightly faster. eventually the opponent will retreat to the castle. there when your angel attacks, you hit the castle too. and eventually you will tear it down without having to deal with the enemies' guardian. if your angel is slower, retreat to a safe distant, use mobs to distract and count the time difference carefully. took me slightly more than 1 hour. heal will give your angel some error margin.
@Beverice the final bosses have crazy fire and poison resistance. if you relied on those in the previous levels, they won't do anything to the wave 50 bosses.
cannons do the most damage. freezers or shockers slow them down. gold makers keep you cash flowing. keep the minimum number of towers you need and upgrade the reload and range of the most powerful gun so it levels up fast. that is all you need to win a game.
too easy 4/5. just throw in a few freezers and upgrade the best gun so that it reload in 8 and cover the whole map and watch it deals 20000+ damages in wave 50