Nulls Hay Day is a mod apk that is used to play a friendlier version of the game where you can get more resources in less time. If you want to know where to get this program you have to read this.
Nulls Hay Day as such does not exist, since it is only available for other video games, but nevertheless there are other types of MOD apk, in which you can play Hay Day without restrictions and get all the resources you need with the least amount of effort.