You've already had some great responses and I can't add much to those. However what I will do is ask you a question - what are you good at writing? (Or at least, what type of fiction do you enjoy writing most, which often although not always amounts to the same thing.) Maybe you have an old set of stories that could be brought to lief / a character you've written about before who is maybe ready for a new adventure.
One thing I'm a little concerned about from your point of view is that most people who end up making point and click adventure games tend to be people who have loved playing them over the years. I may be wrong, but it looks more like this was maybe a commercial decision for you. That's not to say that (if I'm right with that assumption) you won't be able to make good or even great adventure games of course. If you really can't think of an idea you're enthusiastic about enough to develop (and let's face it, making an adventure game really is a labour of love), maybe you can start with a book / film that you particularly love, and go at a tangent from there, then develop your own characters.
I'm also not entirely sure what your "short but sweet" approach will mean in real terms - short adventure games? Short episodic adventure games as part of a season that has its own storyline?
One thing I'm a little concerned about from your point of view is that most people who end up making point and click adventure games tend to be people who have loved playing them over the years. I may be wrong, but it looks more like this was maybe a commercial decision for you. That's not to say that (if I'm right with that assumption) you won't be able to make good or even great adventure games of course. If you really can't think of an idea you're enthusiastic about enough to develop (and let's face it, making an adventure game really is a labour of love), maybe you can start with a book / film that you particularly love, and go at a tangent from there, then develop your own characters.
I'm also not entirely sure what your "short but sweet" approach will mean in real terms - short adventure games? Short episodic adventure games as part of a season that has its own storyline?