"It was a completely overwhelming experience," he said. "So much of filmmaking is conducted in a bubble - you never truly know what you have until it's shown. So to have the Venice audience respond in the way they did just blew me away."

The critical response to the film was also warm. Trade magazine Variety called it an "impressive feature debut". The Guardian said its "down-at-heel Aussie vibe prompts one to set it alongside other recent bawlers and brawlers, such as Kriv Stenders' Boxing Day or David Michod's Animal Kingdom".

West of Sunshine was shot over 18 days in Melbourne and is based on Raftopoulos' award-winning 2011 short film Father's Day.

It stars Damian Hill as sad-sack Jim who is given one day to pay off a $15,000 gambling debt to a violent loan shark. His efforts to raise money are complicated by his compulsive gambling and the fact he has to look after his young son, who is on school holidays.

There is a melancholic tone to the proceedings as Jim proves himself his own worst enemy. Even when he wins big at the races, he can't resist another flutter.

Writing in The Hollywood Reporter, Harry Windsor praised Raftopoulos' use of the location: "The town's ubiquitous cranes and construction sites form an elegant widescreen metaphor for the film's endlessly fraying central relationship."

The central father-son relationship is loosely inspired by the 1948 Vittorio De Sica classic Bicycle Thieves, where mishap leads to a greater familial bond.

"I wanted to do a father-and-son relationship in a neo-realist style with a man under pressure and have him face his own demons," said Raftopoulos. "It's a meditation on fatherhood, and the theme of West of Sunshine is that love is an action and it's not something that you necessarily feel."

After earning awards in Australia for writing and starring in Pawno, also set in Melbourne's western suburbs, Hill is proving to be a talisman for local, low-budget breakout films. West of Sunshine was a family affair for the actor, as playing his son Alex in the film is his real life stepson Ty Perham. Both Hill and Perham were in Venice for the premiere.

"He's been with me for about eight years," said Hill of his 12-year-old stepson. "So that made developing the relationship between us easier."

Perham, he says, came into his own in his first acting role.

"On the first day, I felt like a dad on set, but after the first day he wanted to be with other people in the crew," said Hill.

"It was kind of weird because it was like working and parenting to a degree, but he was beautiful and everybody indulged him."

The Guardian's Xan Brooks said father and son both "deserve credit for excellent, affecting performances".

The film screened in Orizzonti (Horizons), the section of the Venice Film Festival dedicated to new trends in world cinema, and is a contender for the Orizzonti Best Film Prize, to be announced on Saturday evening in Italy.

Running at a sprightly 78 minutes and co-starring Kat Stewart, Tony Nikolakopoulos and Arthur Angel, West of Sunshine is scheduled for an Australian release in August next year, after playing at more major film festivals.