For more than two decades, San Diego's Learning Upgrade has developed "handcrafted" video games that use music to teach reading and math.

A core group of about 10 workers stayed together through the ups and downs at the small family business, helping it navigate technology evolutions from computer compact discs to web-based online lessons to .

Recently, those years of under-the-radar work received big-time recognition. Learning Upgrade was named the co-winner of the $7 million Barbara Bush Foundation Adult Literacy XPrize, beating out more than 100 teams from 15 countries.

"We were in complete shock," said Vinod Lobo, founder of Learning Upgrade. "Most of my team—meaning the artist, the programmer and my parents—have been working together for 20 to 25 years. Yes, we have helped 2 million people over the years who enrolled in our courses, but no one knows about us. So this was a mind-blowing event in the history of the company."

Learning Upgrade shared the XPrize with People ForWords—a team based out of Southern Methodist University in Dallas. Each will receive $2.5 million, in addition to the $100,000 they took home last summer for being named finalists.

Launched in 2015, the Adult Literacy XPrize—presented in partnership with the Dollar General Literacy Foundation—challenged teams to develop mobile apps that could teach literacy to who were reading at or below the third-grade level.

According to the XPrize Foundation, 36 million adults in the U.S. have low literacy skills. Former First Lady Barbara Bush believed literacy was fundamental to success. Unemployment rates among low literacy adults are twice the national average. And there's a generational carryover. More than two-thirds of children of low literacy parents struggle with reading.

"Just imagine trying to find a job, get a driver's license or understand your child's report card without the ability to read and write," said former Florida Gov. Jeb Bush in a statement. "We launched this project to leverage the power of competition to infuse innovation and fresh ideas into the adult literacy landscape."

The Adult Literacy XPrize winners were announced Feb. 7 by Jeb Bush on a yacht cruising off the coast of Miami. The event was part of the Florida Celebration of Reading, a fundraiser for the Barbara Bush Foundation for Family Literacy. Lobo and his wife, Sheryin, were flown out for the event—along with representatives of other finalist teams.

"This is the 30th anniversary (of the Florida Celebration of Reading) and also the first time both Barbara Bush and George Bush were not there," said Lobo. "It was kind of an emotional event."

Upon returning to shore, Vinod and Sheryin set up a conference call with family and key employees on the West Coast to share the news.

Learning Upgrade is a tight-knit outfit. The company is owned by the couple and Vinod's parents, who moved to the United States from India when he was 7. There are no investors and no debt.

"We have done everything on a shoestring," he said. "You do it because you love doing it."

Lobo's mom, Shyla Merle Lobo, is a teacher and songwriter who pens the music for Learning Upgrade's lessons. Video game designer John Banks and animator Ray Blavatt have been with the company for years. So have many of the singers, said Lobo.

Everyone works out of their homes. The lessons themselves have a "Schoolhouse Rock" feel but with more depth.

"We handcraft these lessons that are music and video and games," said Lobo. "We have humor, variety, songs of different genres. It's entertaining."

Over the years, Learning Upgrade has produced roughly 1,000 literacy and math lessons. About three years ago, the company saw a dramatic shift in its business when it began offering smartphone app versions of lessons that previously were tailored for online computer users.

More adults began using its technology—including at the Umi Learning Center for North African refugees in San Diego and the Sweetwater Adult School program in Chula Vista. Three school districts in Los Angeles use the app version of Learning Upgrade in migrant family education programs.

"In our case, we can track all the learning," said Lobo. "We can tell you Joe played on Saturday night, and he is having trouble with double vowels. Suzie is reading stories well, but her social studies textbook reading is not as good."

The non-profit XPrize Foundation organizes contests to spark big leaps in innovation. Past competitions involved building a private, reusable spacecraft and a handheld medical diagnosis device similar to the fictional Tricorder from Star Trek.

Last summer, the Adult Literacy XPrize narrowed the field of contestants to five finalists. One dropped out, leaving Learning Upgrade, People ForWords, AmritaCreate of India and Cell-Ed of Oakland.

The finalists' apps were tested on a combined 12,000 adult learners in Los Angeles, Dallas and Philadelphia. Winners were determined by the greatest literacy gains among both native English speakers and non-English speakers.

Learning Upgrade won $1 million for the best test results among English speakers, while People ForWords took a $1 million prize for non-English speakers. The two firms split the $3 million grand prize.

The contest is not over. There's also a $1 million Communities Competition this summer. It aims to get the four finalist apps into the hands of as many low literacy adults as possible—either through traditional programs at libraries and schools or non-traditional methods such as employers, public housing providers or YMCAs.

For example, a chicken processing company with thousands of employees plans to offer the apps to its low workers, said Lobo.

Organizations and employees who participate in the Communities Competition are potential future customers for Learning Upgrade, said Lobo, which should help the company grow.

"Now we can say without anyone arguing that our program does help a learner make a significant gain," he said. "So now it is a little easier to go to a Google or a Gates Foundation or whomever and say, A: It works with a large sample, and B: All people need to do is download the app and use it."

He continued, "Can we serve millions of users every year in a sustainable way? That would be the dream, to scale up to serve millions of users.—Union-Tribune columnist Diane Bell contributed to this report.