I registered just to see what the puzzles were. Some thoughts:

I found that you can answer the same puzzle multiple times, which you probably want to change.

For three of the puzzles, if you submit a blank form the website breaks.

You should make it more obvious how many sickles a user has. And why are they sickles anyway?

I don't know if this breaks your idea, but maybe add trivia questions as well as puzzles. That might be helpful when you're struggling to find new puzzles, and if a theme built up it might help build a community.