Sorry for the wait! I think there are several reasons the development for "The Pirate Mermaid" takes longer. For one, we are a small team (only two people) who make games as a hobby in our spare time. If we could devote all our time and energy to working on the game, like an actual game company, it would definitely be done much faster. But as it is, we have full-time jobs and other commitments IRL, so the time and money that we can spend on game dev is much more limited. :(
In addition, this particular game is rather long (already over 400,000 words) with many different parts. For example, the script has a lot of branching because of the karma system, and the coding can get pretty complicated because we have so many expressions, animations, and other special features. A shorter game with more basic features probably wouldn't take as long to complete. ^^; But we wanted to push ourselves to make the best game we can, so we need more time to complete everything to the desired quality.
I hope that helps clarify things, and thanks very much for your interest!