Like many 13-year-old boys, Hunter Allis loves video games. His dream is to create them.

Allis also suffers from a rare congenital heart disease called hypoplastic left heart syndrome. The left side of his heart is unable to effectively pump blood to his body.

Thanks to the Make-A-Wish Foundation and mobile app developer Bottle Rocket, Allis got the chance to live out his dream. He created a game called Planet SCRAM that made it to Apple’s App Store.

In Planet SCRAM, which was released on Monday, characters fight against giant tree creatures that shoot snakes out of their head, as well as other types of monsters. Players explore the world while shooting at opponents who are attacking them.

Allis, who lives in Connecticut and started developing the game with Bottle Rocket in 2015, told CNBC that in his younger days he would fill sketchbooks with drawings of his future video game bosses. SRAM’s concept art, characters and game levels all came straight from Hunter’s ideas and drawings.

“I was flipping words around related to my ideas when I realized SRAM spells Mars backwards,” Allis said. “It fit into my backstory of a rocket ship crashing on a planet and needing to survive by beating different creatures.”

Bottle Rocket, which creates apps for other companies, was tapped by Make-A-Wish to help with the project.

“He wanted to combine his creativity with technology to build an awesome experience to inspire and entertain others,” said Bottle Rocket founder and CEO Calvin Carter. “It was an easy decision for us to grant Hunter’s wish.”

Allis signed a week-long contract to work with Bottle Rocket. He got to write his ideas on a whiteboard, come up with features of the app and get involved with game development.

Hunter, who’s moved from sketchbooks to computer graphics, will soon attend a magnet school, where he will focus on game design.

“Hunter’s dream truly moved us,” Carter said. “It gave us perspective. It gave us empathy. And most of all, it gave us hope. We hope that there are more people out that there who will share their unique crafts and passion with others.”