This UK-produced apocalyptic science-fiction yarn looks as if it was made with just enough budget to cover a couple of lights, petrol, the delightfully clunky visual effects – the digital equivalent of sticky-back plastic and pipe cleaners – and a few sandwiches for the cast and crew. But props are due to writer-director Simon Cox, the several dozen producers credited and cast and crew who sunk time, money and effort to make something so ludicrously ambitious with such meagre means, even if the end result is markedly uneven.

The main protagonist is Tom Dunn (Simon Haycock), a psychiatrist living in the London suburbs with his school-teacher wife Mandy (Lucy Drive), who has just discovered she’s pregnant. This is bittersweet news for the couple who are still grieving the death a few years earlier of their small daughter, but both are trying to be hopeful and positive. That’s going to be needed because it looks as if the world is on the brink of war and aliens have invaded. The extraterrestrials kidnap Tom and a handful of his most eccentric patients, setting on them off on bizarre adventures seemingly engineered to make them confront their deepest fears and traumas.

It’s not entirely clear if these head games from another planet have good or ill intentions, but one thing is clear: they must have been watching a lot of vintage sci-fi, especially the Terminator and Matrix franchises, judging by their taste in spaceship interior design. The performances, apart from those of the lead actors, are often painfully stiff, but presumably the cast had to do a lot of reacting to tennis balls on sticks in green-screen studios. That’s hard work for sure.

• Invasion Planet Earth is released in the UK on 5 December.