Random Events
Throughout the game, there are several random events that can occur. This is by no means an exhaustive list yet:
Farm Events
Meteorite
There is a random chance that a meteor can fall from the sky onto The Farm at night. There is no specific year, day or season that this will happen. The screen will go black before displaying the daily earnings window and a unique sound effect will be heard. In the morning, a message will pop up saying "An explosion was heard in the night..."
Meteorites require a Gold Pickaxe or better to mine. It drops Iridium Ore, Stone and Geodes.
The Crop Fairy
During any of the growing seasons, there is a chance for the Crop Fairy to appear once you go to bed. She will select a a certain number of tiles that contain a crop you're growing, and that number may, or may not be random. Everything from a 1x1 area to a 5x5 area has been reported. This area will then immediately be available for harvesting the next day, no matter what growth level the crops were at previously.
The Witch
In a random event after you sleep, a witch will fly over your Farm.
Coop
If she flies over one of your Coops, she will leave you with a Void Egg in the morning. This can occur on an empty, or full coop. Incubating the Void Egg will result in a Void Chicken.
Slime Hutch
If she flies over one of your Slime Hutches, she will turn all of the Slimes into Black/Transparent Slimes
