Returning the favor, Greenberg showed him around the Microsoft campus and introduced him to as many people as he could, even barging into Xbox chief Phil Spencer's office without an appointment so Wigal could tell his story. "Phil was probably on the phone, but I didn't care," Greenberg told me. "[Wigal] is doing great work, so I raised my hand and said I'm gonna be his hype man."

In 2016, GO received a gift through Microsoft's corporate giving campaign. One philanthropic event involved a pie-throwing contest. Employees bought tickets, exchanged them for tinfoil pans full of whipped cream and hurled them at management. Greenberg was a willing target . In one day, Microsoft employees raised $5,000 for the foundation. For an idea of how many pies he caught with his face, Greenberg told me the next day he still smelled like Cool Whip and even had some lodged in his ears.

He didn't stop at taking pies to the face. Using the GO fundraising platform, he recruited others to help fill Seattle Children's Hospital's need for an additional nine Karts. Using his position in the gaming industry, Greenberg reached out to people like Game Awards host Geoff Keighley, Electronic Arts exec Peter Moore and HoloLens creative director Kudo Tsunoda to donate and help spread the word online. Even electronic musician Steve Aoki got in on the action.

"We play our games, and we love gaming as an art form," Greenberg said, "but to be able to tie it back to something where [games] mean even more to kids in hospitals? I don't know how to describe the feeling I get."

Greenberg paid for two Karts out of pocket, and tasked the gaming community to raise the additional funds for the remaining seven. With high-profile streamers helping out, Greenberg's fundraising campaign brought in $12,599. Streaming app Infiniscene, a 2016 Gamers for Giving sponsor, matched those donations, pushing the total past $25,000. Greenberg said this success overshadowed all the work he'd done for Microsoft in 2016 -- including launching Forza Horizon 3 and Gears of War 4.

"It was the most important thing I focused on this holiday," he said.

Expanding into more facilities is Wigal's ultimate goal. More visibility thanks to celebrity endorsements will ultimately advance that mission, but it isn't the point. However, Wigal expressed deep gratitude for the work people like Greenberg have done for GO.

"I see it as a pathway for growth," he said. "But not the pathway." The real method for expansion is empowering gamers to fundraise, getting the word out about the foundation and combining those with in-house fabrication. As of this writing, there are more than 50 fundraising campaigns listed on the GO website at various stages of completion. But all the fundraising campaigns in the world won't do much good if GO can't supply the Karts to hospitals.