The game forces you to come back
Just like Clash of Clans Hay day forces players to keep coming back to harvest their crops and do the other important tasks.
The game remains at the back of the mind
As each task takes some time to complete , usually more than few minutes, a person who exists the game keeps thinking about those tasks because they aren’t yet finished. This fact makes the game more addictive.
Escaping to a new world
The game’s graphics are impressive. They resemble a real world farm in a cartoon-like way. This allows people to escape to a new world and enjoy their time there while forgetting about their real problems.
Graphics are pleasent
The very colorful Cartoon-like environment gives players a joyful feeling. When a person sees those images and colors he feels happy and so becomes more motivated to continue.
The desire to unlock new features
As soon as the game starts the player realizes that there are so many interesting things that can only be unlocked as he keeps progressing. This motivates players to keep playing.
A sense of responsibility
Players feel a sense of responsibility towards their farms. They know their chickens might be Hungary or that people are waiting for the eggs to be sent and as a result they return back to the game.
Forced into loops
Many actions in hay day are dependent on other actions. For example in order to sell eggs you must wait for chickens to deliver them and that won’t happen unless the chickens were fed well. Those kind of loops force people to keep playing. (See Why is clash of clans so addictive?)
Notifications bring players back
Notifications such as ‘The Milk is ready’ makes players feel compelled to come back to the game.
The game feels realistic
Most of the elements in the game are borrowed from real life. A player feels that he is actually responsible for a real farm and this increases his sense of responsibility towards it.
Nostalgia makes it addictive
The game reminds players of Cartoons. This adds an effect of nostalgia that makes the game more popular.
The social element
The game includes a social element where players can connect with each other. Because humans are highly social beings this social element makes the game more addictive. (See Why Online Games are addictive?)
How long does it take to rebuild the gem mine in Clash of Clans? How to find and repair the gem mine?