When Julia Minamata started building her Agatha Christie-style mystery house, it was just with furniture and windows.

It was a creative exercise, “a bunch of hobby illustrations” not meant for other people to see.

But it is now.

Minamata, 38, a freelance illustrator from Scarborough’s Malvern neighbourhood, turned the house into a story and the story into a video game, The Crimson Diamond.

“It didn’t start off as me wanting to make a game,” she said at University of Toronto Scarborough, where she once took courses.

The Crimson Diamond is a “cosy mystery” adventure, where a single player goes around exploring, asking questions, and examining objects.

It hearkens back 30-or-so years to adventure games Minamata was most drawn to as a child, including The Colonel’s Bequest (1989), a favourite also set at an isolated location in the past.

Minamata visited Malvern Public Library a lot, and was a fan of Nancy Drew, the Hardy Boys and Gordon Korman. “I was a huge reader as a kid.”

Though she’s “always dressed in greys and blacks,” The Crimson Diamond uses the bright “retro” colour scheme Minamata likes, known as EGA 16.

A character she created to check the scale of her imaginary house became Nancy Maple, a go-getter mineralogist the Royal Canadian Museum sends to Crimson after a diamond is found inside a fish.

The story itself is “fairly linear,” with “not a lot of opportunity to die, not a lot of ways to directly fail,” said Minamata, whose illustrations have appeared regularly in Maclean’s and the National Post.

“I want to give the players a good experience.”

Part of that is using a text parser to type her character’s questions.

Minamata considers this engaging, but doesn’t expect players, even those who were around 30 years ago, to find it familiar.

The game and its developer were part of Toronto’s EGLX at the Metro Toronto Convention Centre, Oct. 18 to 20, and Minamata was set to join AdventureX 2019, a showcase of adventure games, from Nov. 2 to 3 in London, England.

Working on a game yourself produces something unique and personalized, but it can be isolating.

Watching player’s reactions, she said, she sees what to fix or adapt.

Though they had technological limitations, old-school adventures like The Colonel’s Bequest were produced by small teams — again, unlike many games built today for broad audiences by companies employing hundreds of people, said Minamata.

“People are interested in experiencing different stories,” she said, including “people like me, who don’t respond to shooty-shooty kind of games.”

At University of Toronto Scarborough’s Rock Walk, Minamata looked at glacial boulders formed by a process of heat and pressure, changed, she said, like Nancy in her game.

“At the end, she has to make certain decisions that will impact her future.”

The Crimson Diamond will be sold on Steam and itch.io