The Hills Have Eyes Movies: Classic Timeline
The original Wes Craven timeline consists of his 1977 cult classic and its widely panned 1985 sequel. While the original remains a landmark of '70s horror cinema, the sequel is considered one of the worst horror sequels ever made.
Craven himself disowned Part II, which he only directed out of financial necessity after the poor reception of his previous films. The sequel is infamous for excessive padding with flashbacks to the original film and features a notoriously absurd flashback sequence for a dog. Most fans consider the 1977 film a complete story on its own. You've been warned.
There are 2 other watch orders available - see the links up above.

The Hills Have Eyes
When the Carter family's RV breaks down in the remote desert, they become trapped and terrorized by a clan of savage cannibals hiding in the nearby hills.

The Hills Have Eyes Part 2
A motocross team ventures into the desert to test a new super-fuel, unaware that their guide Rachel has a dark connection to the area's dangerous past. They soon find themselves facing the same deadly threats that plagued previous visitors to this remote wasteland.
Other Film Series
Edgar Wallace
German crime thriller series from 1959-1972 that created a distinctive subgenre of atmospheric gothic mysteries, featuring recurring cast and iconic villains.
Friday the 13th
The murderous legacy of Crystal Lake and its iconic killer Jason Voorhees in this enduring slasher series.
It
The Losers Club faces off against Pennywise, a shape-shifting entity that terrorizes the town of Derry every 27 years.
Open Water
An anthology of standalone survival horror films about people stranded at sea, with no narrative connections between installments.
Paranormal Activity
A found-footage horror franchise following the demonic entity Toby's terrorization of the Rey family across multiple generations.
The Purge
A dystopian horror franchise set in an America where all crime is legal for 12 hours once a year during an annual event called The Purge.