I had the same problem initially. I had an idea but couldn't work out how to make it into a game. So I wrote down lists of Christmas things: Christmas places, Christmas icons, Christmas stories, Christmas movies and so on. I did a lot of research (thanks Google). After a while, things started to fall into place. I actually started with a map and populated it with characters and objects as puzzles started to suggest themselves.
In answer to your original question, I think it now rates as a 5.