It's difficult, keeping indoor cats physically active and mentally stimulated enough so that they don't shred your entire house to bits out of boredom.
I think they amuse themselves by suddenly deciding that no, I no longer like that toy. Then they sit and stare at me until I figure out what they want to play with. I call it the "making the human look like an idiot" game. I think it is their favorite.
Thor's new favorite game is chase the feathers on a stick toy but only on the bed in the spare room.