not every game out there that has exploration and some thinking would be considered an adventure, and any game with (action) scene as you said Gabe should be treated wisely and also it should be tagged with something like that (explicit words) for music CD's
,something like watchout this game has, timed scene,Shooting,Fighting,driving ..and so on
i sure double Tim just fine
but he himself shoudnt bother about a definition for AG when he had given a game like staking already, he knows better. and he is one the developers out there that AGers depend and trust about evolving the Genre !