One clue is the amount of gaming (it's pretty subtle, I know, you've got to have an eye for that).
Another is, uh, the pleasure ? Or the concentration ? When you play hoping that the level or game will end soon, or while thinking about everything except what the character is doing in that virtual world, maybe you're not quite in a gaming mood ? That said, it's a continuum. You can play casually, in the grey zone between not wanting a game and not wanting to do something else...
But usually the causes here are :
- Saturation ("been there done that" enough for a while).
- Distraction (other actvities or events, more stimulating because more pleasant or more meaningful, hooking you for a while).
Gaming is a bit like sherlock holmes' cocaïne, the way I see it.