The Flyers rebuilt the team when they traded two of their cornerstones, Richards and Jeff Carter, with Carter going to Columbus.
"Shock," said Richards, who had signed a 12-year, $69 million extension that took effect with the 2008-2009 season.
He said the shock took a little time to wear off.
"Once I got to know the [Los Angeles] area, it helped out," said Richards, who spent six seasons with the Flyers, reaching the Stanley Cup finals in 2009-2010. "I am just happy again playing."
If Richards wants any advice on how to face a homecoming, he can talk to former Flyer Simon Gagne, who is his Kings teammate.
Like Richards, Gagne is a former first-round draft choice of the Flyers who spent considerable time in Philadelphia. In Gagne's case, it was 10 seasons before being traded last season to Tampa Bay. He signed with the Kings this season as a free agent.
"It took a while to realize I wasn't with the Flyers and was with Tampa Bay and not wearing the jersey," Gagne said.
His first game back to Philadelphia wasn't easy for Gagne.
"It was definitely weird walking across the locker room to the other side," Gagne said. "It was one of the toughest days in my career as a player, and I guess it is not going to be easy for Mike."
Richards says it's nice to be surrounded by some familiar faces such as Gagne and Kings assistant coach John Stevens, the former Flyers head coach. No longer a team captain, Richards said it has been easy to fit in with his new teammates.
"The guys in the dressing room have helped out a lot and made me feel at home," Richards said.
Stevens, now in his second season as a Kings assistant, understands the significance of Richards' return to the Wells Fargo Center.
"When you think of Mike Richards you think of Philadelphia, so this is certainly a big event for him and for the fans," Stevens said.
Richards made a strong debut with his new team. The Kings opened their season in Europe, beating the New York Rangers, 3-2, in overtime in Stockholm, Sweden. Richards scored a goal and assisted on the game-winner.
"He has a lot of leadership and is a character player with a winning attitude," said Kings coach Terry Murray, yet another former Flyers head coach. "For the Kings he gives us more strength down the middle of the ice."
Richards said he still keeps in touch with some of his former Flyers teammates. In fact, the Kings landed in New Jersey on Monday, and Richards said he went to dinner with the Flyers' Scott Hartnell.
He said that he'll always have a good feeling about Flyers fans.
"I enjoyed playing in front of them every night and was excited to play in front of them," he said. "And I will be excited to play in front of them on Saturday."
Contact staff writer Marc Narducci at 856-779-3225, firstname.lastname@example.org,
or @sjnard on Twitter.