It may not be particularly great sci-fi horror, but for the series’ devotees, Ridley Scott’s Alien: Covenant is certainly a first-rate exercise in nostalgia. Look! There’s the title gradually appearing in vertical, horizontal, and diagonal lines! There’s the futuristic “burial at sea” with a mummy-wrapped corpse! There’s the derelict spacecraft! The face-hugger! The drinking-bird tchotchke! The heroine with the Sigourney-in-combat ’do who shouts, “We’ll blow this f----- out into space!”