Gaming is an activity that I filed under mindless, I don't play many games these days but I have in the past and generally noticed myself eating less. Typically when I play games these days I listen to an audiobook or podcast at the same time and my attention is on the audio more than the game, for which I'm basically on autopilot.

I never been big on puzzle games though, I prefer games like doom or quake. Fast games that focus on reaction time and spatial awareness, rather than problem solving. If I were playing something slow and complex (chess, minesweeper, etc), I expect I'd probably be more aware of my hunger.