The chat fiction stories offered in Mammoth Media‘s mobile app Yarn are about to get more interactive.

The branching narrative mechanic should be familiar to anyone who read Choose Your Own Adventure books when they were kids — you read a story, and, at certain key moments, you choose from different options that determine where the plot will go next.

More recently, the “Being Beyonce’s assistant for a day” thread on Twitter reminded everyone how fun and stressful this kind of storytelling can be. In fact, Mammoth says it’s hired the thread’s author Landon Rivera as one of the writers for this new initiative.

One thing you probably won’t recognize from your childhood reading is the fact that some of these choices aren’t free — to select them, you’ll need to spend money in the form of Yarn’s new virtual currency, gems.

Mammoth founder and CEO Benoit Vatere explained that in those cases, there might be two choices that you can select for free, plus a third that you need to pay for. Usually, it will be something that accelerates the story or sends it off in a new direction — in a horror story, you could get the option to stab someone, or in a romance story, your character could get the option to go home with someone.

Vatere added, “It’s not only being able to have a different branch in the story, but being able to play as a different character lead … Instead of being the male character, would they like to be the female character and really see a different perspective?”

He acknowledged that some of Yarn’s paying subscribers might be cranky about being asked to pay more, but he said the goal is that those subscribers can have “a full experience” without having to buy additional gems.

Yarn is launching interactive stories with titles including “Blue Ivy’s Nanny,” where it’s your first day on the job as Beyoncé’s nanny (I’m going to go ahead and guess that Rivera worked on this one); a romance story called “Playing the Field;” a horror story called “Haunted Camper” and a drama called “Trapped.” Vatere also said there are plans for branched narratives tying into existing Yarn franchises, and set in the world of Archie Comics.

Overall, Vatere said he’s hoping that this will lead to more engagement from Yarn readers, while also opening up new opportunities for monetization.

“Subscription is a great model, but subscription has a cap,” he said. That’s why Mammoth is experimenting with virtual currency, and why it plans to make these stories available to non-subscribers.