Director Ridley Scott has choice words for anyone who thought Prometheus (2012), the first of several planned prequels in the Alien franchise, was stuffed with too much philosophy and too little horror.

"'Get a life.' That is my reply," says the 79-year-old four-time Oscar- nominated titan of the film industry.

Prometheus won much critical acclaim, but many reviewers felt its lofty ideas of genesis, at the hands of the god-like Engineers playing with mystical black goo, were too cerebral and mysterious. After all, this is a franchise known for space monsters that use humans for baby food.

"It's hard to make these things," he adds, as if to say it was unfair of critics to judge the film without understanding how difficult it is to create something of that scale.

He was speaking to the media in June last year, when the studio 20th Century Fox took journalists in Sydney, Australia, on a tour of the sound stage of the new prequel, Alien: Covenant. The film opens in Singapore today.

Scott, director of Gladiator (2000) and The Martian (2015), says the new film takes up "the evolution of the grand idea" put forward in Prometheus, which hinted that the Engineer race created life on Earth, as well as the deadly Xenomorph creatures, and that the two events are somehow linked.

The unifying theory behind the prequels - tying together the Engineers, Xenomorphs and the reason for luring humans to the faraway planet in Prometheus - will be made clear by the time the story catches up with the crew of the Nostromo in the first Alien movie, released in 1979, he promises.

"We are in the middle of the process of showing this grand idea. We are one or two movies away from Alien," he says.

Known for making movies with strong female protagonists, such as Thelma & Louise (1991), G.I. Jane (1997) and, of course, Alien, Scott says that Katherine Waterston, who plays Covenant crew member Daniels, is "right up there" with other great actresses in his films.

"I take great trouble with casting. Even in an action film, you need great actors," he says.

But the real star of any Alien movie is the fanged killer that gives the franchise its title.

For Covenant, creature supervisor Conor O'Sullivan showed journalists a silicone model of the new breed of Xenomorph, dubbed the "Neomorph".

"Everything is based on nature," he says. The Neomorph takes its look from combining the features of a human with those of a goblin shark, which has an elongated head and jaws that telescope out of its face when it feeds.

Mr O'Sullivan says his team worked with the "hundreds of drawings" that poured from the imagination of Scott, who graduated from London's Royal College of Art and, in his early years, worked as an artist and designer.

Costume designer Janty Yates says she also worked closely with Scott on the astronaut outfits worn by the crew of the Covenant. As in the first Alien film, the uniforms are colour-coded by specialisation.

Danny McBride, who plays crew member Tennessee, will, for example, take a space walk in a suit her team have dubbed "Big Yella".

Ms Yates, who won an Oscar for her work on Gladiator, enlisted the help of new-on-the-scene British menswear designer Craig Green for the military-style jackets worn by the team exploring the Earth-like planet, the setting of the new film.

In keeping with the tone set by the 1979 movie, one of the first science-fiction films to show a livedin, dirt-stained spaceship crewed by people wearing crumpled clothes, a chief concern was that the new film should be only "a little futuristic".

Ms Yates says: "We don't want to go too Star Wars or Star Trek, nothing too extreme."

•Alien: Covenant opens in Singapore today.