Still Wakes the Deep follows offshore electrician Caz, played by Newman, and his co-worker Finlay, played by Dunbar, who are trapped on a damaged North Sea drilling platform in 1975.
They are pursued by mysterious monsters and have to deal with terrible weather conditions. Players must rely on stealth and puzzle-solving to stay alive.
The developers – Brighton based games company The Chinese Room – cite classic horror and science fiction films and TV shows such as Annihilation, John Carpenter's The Thing and Sapphire and Steel as inspirations.
The trailer for the game and its soundtrack features the Gaelic song 'Fath Mo Mhulaid A Bhith Ann' (Being Here Has Caused My Sorrow), performed by Maggie MacInnes, and the game has a Gaelic subtitles option.
Project director John McCormack said this was an attempt to reflect its "uniquely Scottish story".
"After listening to 'Fath Mo Mhulaid A Bhith Ann' for the first time, it was clear that the game experience wouldn't be complete without a full translation deeply connected to the history and people of Scotland," he said.
Glasgow-born Alec Newman is perhaps best known for playing head master Michael Byrne in the BBC series Waterloo Road from 2011-2013.
He also played Paul Atreides in the 2000 mini-series of Dune, and has appeared in Outlander, Shetland and Call The Midwife.
A prolific games actor, he thanked the makers of Still Wakes the Deep for giving him the role.
"Your attention to detail is phenomenal, and was an inspiration to me from the moment I first read for Caz McLeary," he said.
Publishers Secret Mode said they were delighted with the awards.
"We're thrilled for Alec and Karen who played a huge part in bringing this wonderful game to life," the company's James Schall said.
Dunbar told BBC Scotland News she was "gob-smacked" to have won.
She said she attended the awards with the hope of meeting one of her favourite actors Matt Berry – star of vampire comedy What We Do in the Shadows.
"Part of the surprise is I was up against Matt Berry and I love him," she said. "I felt I had to go to possibly meet him and maybe mingle a bit.
"When they said my name I started clapping, thinking it was Matt Berry. Then I was like 'Oh my God, it's me'.
"This isn't false modesty," she added. "I know when I'm good and I know when I'm not and I was good in that game."
This was her first video game acting role, an experience she enjoyed and compares to working on a radio play.
Sonic the Hedgehog's mum
Dunbar performed remotely from Glasgow while her co-stars and director were in a studio in London and she believes her relative lack of experience in the genre may have helped free her up to play the role.
"I didn't have any preconceptions, I just played the character. I was ignorant," she said.
Having made the move into a new genre, she is now keen to continue working in games.
"Just to be in that world was so exciting. To see all those new people. I had no idea before and I really liked it, especially at my age when I have done most things," she said.
And while the 54-year-old admits she has never been much of a gamer, the role of Finlay has opened up new opportunities for the future.
"The last game I played was Sonic the Hedgehog, so I would like to to play Sonic the Hedgehog's mum," she said.