For a while during late high school and college, I could not stop playing Pokémon Conquest on planes. I eventually ended up putting close to 100 hours into that game almost exclusively during travel. I’ve since lost the cartridge and really need to replace it.
Two Dots. I know it’s not cool, idc idc. As soon as I settle into my seat I start playing it and leave my 3DS or more recently my Switch in the seatback pocket for the duration of the flight. It puts me to sleep pretty easily and doesn’t prompt a lot of questions from well meaning but nosy seatmates.