Sorry I haven't read the replies just throwing in my 2 cents,
When designing which system you want to use, I recommend totally forgetting everything you know about adventure-game and just think it purely from scratch, when I've done so I've found that the convention is very flawed and there are better ways,
since adventure-games are simple from a game-design perspective it doesn't really take that long to "re-invent the wheel", no need to analys much about how other games has done it.