So Riedel formed a "Baby Boomer" group through his church that hosts regular game nights and weekly dinners.
"When our kids were around, we had reasons to get together," said Riedel, 55, a furniture maker in Auburn, Calif. Now, "we had less excuses to get together, so we invented this."
The group plays everything from lawn games to Connect Four.
"It has nothing to do with the games," he said. "It's really just a social event."
As baby boomers age, many of the traditional ways to make friends disappear, said Lynda J. Sperazza, an associate professor at the State University of New York at Brockport, who studies how this generation spends its free time. Many start looking for new social outlets.
"Recreation and leisure is still of utmost importance. It is critical to their self-concept and sense of well-being," she said. "Game nights and boomer clubs are a means to be active, which is in sync to their values."
The Baby Boomer Club in Sun City Center, Fla., for example, organizes parties, dances and game nights, said president Linda Moore.
"It's strictly a social club," said Moore, who, at 70, is technically not a boomer. "Not everybody in the club is a baby boomer. It's people who want to go out and socialize."
The U.S. Census Bureau defines baby boomers as people born between 1946 and 1964.
That includes Debbie Schwartz, 52, of Mayfield Village, Ohio, who looks forward to a monthly mahjong game with friends.
"It's a real thinking game. It's great for keeping your mind sharp," she said of the Chinese game played with tiles.
Games do help people stay mentally sharp, said Dr. Martha Stearn, executive director of the St. John's Institute for Cognitive Health in Jackson, Wyo. Each fall, the institute holds a Brain Game Challenge with trivia contests, word games, Tai Chi demonstrations, sing-alongs and other activities. But Stearn said the social benefits of games and activities are even more important for brain health than the mental challenges are.
"We are programmed to be social. Isolation is one of the worst things for the brain," she says.
Schwartz, who started the mahjong group 15 years ago, said its six members don't take the game too seriously.
"We use it to talk and catch up," she said. "We've been friends for a long time."
Fellow player Judy Palladino, 57, said she and her husband, Vince, like the excuse to get together with their friends. The husbands often play poker while the women play mahjong.
"We're all older. We're tired. It's nice to come home and do nothing. It's also important to stay active and connected with old friends," Palladino said.
When the couple recently bought a second home, in Florida, they chose a community that organizes recreational activities. "That was really important in our search for a Florida house," she said.
They picked an over-55 community in Sarasota where Palladino has found another mahjong group.
Tracy Weller found a monthly Bunco game when she moved to a new neighbourhood in Wexford, Pa., in her 30s. Gathering with other moms in the neighbourhood to play the dice game was a good excuse to get out of the house, she said. Now 49, Weller is a substitute player in the group; she gave up her permanent spot because her two teenage daughters have such busy schedules.
"I enjoy it when I get to go," she said. "It's my connection to what's going on in the neighbourhood."
She anticipates returning to the group full-time when her daughters head off to college in a few years.
"I expect I will have more time to myself then," she said.