What determines the chances of a coin appearing in an adventure game?

Solution 1:

Unfortunately there is no available source for a specific drop rate from just general zombies, but this is random. There are specific situations that will lead to a drop however:

  • Killing zombies (sometimes coins, diamonds, chocolate, or Zen Garden plants may drop), and killing a Zombie Yeti will drop four diamonds (five on the first sighting).
  • Lawn Mowers, Roof Cleaners, and Pool Cleaners that aren't used (they turn into gold coins after each level and are automatically collected).
  • Marigolds (they drop silver and gold coins, though gold coins are less likely).
  • Completing levels (when mini-games, Puzzle Mode levels, and Survival Mode levels are completed, a money bag or trophy is dropped; clicking on it will cause coins or diamonds to be automatically collected).
  • Eating brains in I, Zombie (coins, diamonds, presents, or chocolate may drop).
  • Every ten levels in Vasebreaker Endless (the last vase or killed Zombie will drop a money bag).
  • Completing Adventure Mode levels after beating them for the first time (the last zombie will drop a money bag with five gold coins in it).
  • From Zen Garden plants (Zen Garden plants drop money after being watered or fertilized, as well as after the phonograph or bug spray is used on them. After the phonograph or bug spray has been used, they also drop occasional coins in a manner similar to Marigolds).
  • Destroying a grave with a Grave Buster (coins, diamonds, presents, or chocolate may drop).
  • Selling Zen Garden plants (directly adds a certain amount of money to the bank balance; this amount depends on the type of plant and its maturity).
  • Slot Machine (sometimes gives diamonds when spun).
  • Completing Adventure Mode will give the player three diamonds.
  • Getting the Gold Sunflower Trophy (five diamonds).

Source