So, if I post a quest game, is it possible for me to know which rooms has the players passed or in which stage do they give up the game?
As only if I know this information, I could know where and how to improve my game.
THx.

There is nothing built into Quest that gives that type of analytics. If you wish to come up with a scheme for doing so (including having a server to read and store the data), others would undoubtedly find it of use!

You can actually do this to some extent using ActiveLit - http://activelit.com. It only works for user accounts that you create for your ActiveLit site though. You get to see full game transcripts when your site users play Quest games.

It's something I've thought about rolling out to the main site at some point. One day! There would have to be a way for players to opt in/out though.

Well there you go... That's very cool!

You could include a request for transcripts and answers to those questions, but that extra step seems like too much effort for even dedicated players sometimes, let alone the more casual crowd here. A lot of time a game uploaded as a zip on ifdb or wherever will have a feedback form included with any other extras, but no idea how often the authors hear back.