# Systems

- [Leash Flags / Requirements](/legacy/systems/leashflag.md): Leash Flags are the requirements that a mob needs to meet in order to become a pet.
- [Skilltrees](/legacy/systems/skilltrees.md): Skilltrees are the way to specify when which pet will unlock/upgrade which abilities.
- [SkilltreeCreator - Tool](/legacy/systems/skilltrees/skilltreecreator.md): The SkilltreeCreator is a tool with which you can create skilltrees for pet quickly, easily and without experience.
- [Experience](/legacy/systems/experience.md)
- [Experience-Script](/legacy/systems/experience/expjs.md)
- [MyPet Storage](/legacy/systems/storage.md): The MyPet storage is way to have more than one MyPet.
- [Hunger-System](/legacy/systems/hungersystem.md)
- [World Groups](/legacy/systems/multiworld.md)
- [Auto Updater](/legacy/systems/updater.md)