Occupation: Rainfall is a Luke Sparke's sequel full of sound and fury

The Australian film industry is small and budgets are generally modest. This goes some way towards explaining why - despite the fine production facilities we have, often used by overseas filmmakers - we don't see a lot of home-grown science fiction movies. There doesn't seem to be enough money to go into making the unreal look real for audiences used to high-quality special effects.

Writer-director Luke Sparke, who's worked in various capacities in film and television, went ahead regardless. I haven't seen his 2018 movie Occupation, apparently made for about $6 million, but it was enough of a success to warrant making this sequel, which I saw at Dendy the night it opened, with a handful of other people in the cinema. While this was my introduction to the world of the previous film, I don't think I was too far behind.

Occupation: Rainfall reportedly had a budget of $25 million, about four times that of its predecessor. That's high for an Australian film but a pittance by Hollywood megaproduction standards. The special effects are variable: many look good but not infrequently there will be inferior CGI imagery and green screen work. Not that this film is the only culprit in that department: you can find subpar work even in big-budget Hollywood movies including the 1996 film Independence Day, which seems to have been one of this film's inspirations.

The alien invaders from the previous film have destroyed Sydney (there is a shot of a ravaged Harbour Bridge) and killed many. Among the resistance members, Amelia (Jet Tranter) advocates for the aliens who have deserted their own kind and become fellow resistance fighters and refugees (fair enough) but also wants to negotiate with the invaders (which seems more dubious).

She's opposed by Wing Commander Haynes (Daniel Gillies), who is happy to torture as well as kill aliens. Any resemblance to contemporary events is hardly coincidental.

Meanwhile, Matt Simmons (Dan Ewing) sets off on a mission to Pine Gap in order to discover what "Rainfall" is - it might help in the fight against the aliens. He reluctantly accepts the company of a serious-minded alien (Lawrence Akaore) he dubs Gary (the back-and-forth regarding this unwelcome moniker is one of the laboured comedy elements).

And, of course, the fight continues.

The film often plays like a fanboy's grab bag of bits and pieces of earlier alien invasion and other sci-fi movies - there's not all that much originality in evidence here. But if it's familiar and cliched, at least it's an Australian vision: people who complain American movies like this are mostly about the US with only passing reference to other countries' fates will find this movie is similarly focused on its own country. And why shouldn't this be so? We're dealing with a particular group of characters' fight for survival: it's not intended to be a global study.

The film doesn't really justify its two-hour-plus running time. There are a lot of explosions and battle scenes throughout the film, and there's not enough fleshing out of the characters: it's hard to care about anyone on screen.

Two other writers are credited with additional dialogue but the script is leaden and clunky. Ideas such as xenophobia and torturing prisoners are raised but skimmed over: it seems Sparke is more interested in spectacle than character and even story. The sound mix often favours the music, gunfire and other sounds above the dialogue, which doesn't help dispel that notion.

This is yet another Australian film where foreign talent has been brought in to make the film more attractive internationally: are Americans still so insular that they need to hear at least one character with a US accent? The answer, apart from the art-house circuit, still seems to be yes. But the comedy relief intended by Ken Jeong (The Hangover) as a paranoid scientist at Pine Gap and Jason Isaacs (the Harry Potter movies) voicing his laid-back alien sidekick falls pretty flat, not helped by being placed late in the film when the story needs to be resolved.

Despite its flaws and familarity, Occupation: Rainfall is an ambitious undertaking that shows there is still room for genre filmmaking in Australia.

The end is, inevitably, left open for another sequel. Whether one emerges will depend on how well this film does: will the inflated budget be matched by increased interest at the cinemas and digitally?