Simplify the following text for a Grade 6 native English-speaking person.
Original: ZONE was once sold by WizardWorks , which included over 500 fan-made levels .
Simplified: Zone ( Parts 1 and 2 ) : Was sold by WizardWorks and had over 500 levels made by fans of Duke Nukem 3D . ZONE II , contained three episodes designed by WizardWorks .