While it's part of the "Halloween" franchise, it was a deliberate attempt to move away from the slasher formula and tell a standalone story about a mysterious conspiracy involving a creepy mask manufacturer and a sinister plan to control children's minds.
This decision led to the film being a box office disappointment and causing a rift between the director and the producers. The franchise ultimately returned to its roots with the next installment, "Halloween 4: The Return of Michael Myers."