Skyline should’ve starred Casper van Dien and Coolio and stayed sequestered on SyFy, to be giggled at en route to more promising programming.

Given potential legal action awaiting directors Greg and Colin Strause (hubristically crediting themselves as “The Brothers Strause”), it might have also wisely reduced their liability on this alien-invasion action film.

Set aside Skyline’s dull, unremarkable nature as a reason to hide it from critics; business sense suggests that might have staved off process servers a bit longer.

The Strauses directed this film about the military attacking aliens that invade Los Angeles. The Strauses served as visual-effects supervisors for Battle: Los Angeles, a 2011 Sony film about the military attacking aliens that invade Los Angeles.

You see where this is going: Sony wonders why the Strauses kept Skyline on the QT and whether they appropriated technology developed for Battle to squeeze Skyline out on the relative $10-million cheap and months before Battle.

Derivative enough to be called Adherence Day, Skyline knocks off so many other alien-invasion films you can hear the Strauses’ commentary referring to the Cloverfield moment and the District 9 moment. (The Strauses didn’t write the screenplay. They left that to other visual-effects people, Joshua Cordes and Liam O’Donnell.)

The Skyline moment? Future filmmakers won’t reference any such thing.

The Strauses claim 20th Century Fox butchered their 2007 directorial debut, Alien vs. Predator: Requiem. That may be, but Skyline, filmed and financed on their own, does little for their claims to competency — their production-company names like Hydraulx and Transmission attached to a real jalopy.

Its mere 15 minutes of exposition are so bad that the film must flashback to them after an opening scene of initial alien contact.

Jarrod (Six Feet Under’s Eric Balfour, still looking like an eraser with a face and goatee) and girlfriend Elaine (Scottie Thompson) fly to L.A. to celebrate the birthday of Jarrod’s best bud, Terry (Donald Faison of Scrubs). Surprise! Terry is a visual effects man living like a gangster — with a trophy girlfriend (Brittany Daniel), comely assistant (Crystal Reed) and posh penthouse suite. (Skyline was filmed largely in and around Greg Strause’s condominium complex, no doubt left standing after its shellacking to appease the condo association.)

After a night of hard partying — and revelations of pregnancy and infidelity — the group awakens to blue light streaming through the remote-controlled blinds.

In Skyline, burst capillaries come not from violently regurgitated Patron but from the blue light’s tractor-beam powers: Stare at it, get vacuumed into spacecraft that look like hovering tortoises and have your brains swallowed like shrimp cocktail, which Jarrod and Elaine narrowly avoid.

The automatic blinds open whenever the Strauses need to turn up the heat on their special-effects sizzle reel — revealing an L.A. under siege by aliens resembling, in various incarnations, crustaceans, Rock ’Em Sock ’Em Robots and octopi you see atop car washes. (Creature designers Alec Gillis and Tom Woodruff Jr. do what everyone else without extraterrestrial innovation does: Crib Alien’s H.R. Giger.)

Our heroes must weigh the risk of venturing outside (“The spaceships aren’t over the water, so we can escape by boat! Right?”) or staying put and waiting for rescue.

Venturing outside goes badly (especially for Faison, yanked into something smellier than the last season of Scrubs). But so does staying put, as the aliens find their way into the complex.

From there, Skyline’s two centerpieces are airborne strikes undertaken by drones as remotely operated as Skyline itself. They amount to nothing more than a nuclear kick to a hornet’s nest and a laughable suggestion from Jarrod (ever the brainiac), who’s itching to go outside, that radiation will kill them in the condo.

Flood the market as they do with technically impressive money shots, the Strauses endow Skyline with as little excitement as they do common sense — leading to a goofy conclusion that looks like a cheaply made live-action version of Bionicle.

For all the bombs bursting in air, Skyline is just a TV star-spangled bummer.