Question: What was Reid and Gideon's favorite plane game?
On plane rides to and from cases, Reid and Jason Gideon enjoyed playing chess. Reid struggled to cope with the murder of his old boss in Season 10. While the team investigated Gideon's murder, Reid continued the chess game that his old friend had started. Before leaving, Agent Rossi joined in an effort to both finish the game and help Spencer move on.
"Nelson's Sparrow" (Season 10, Episode 13)