I've recently put all of the puzzles on a single map and connected them via major hub areas. This means that it is now possible for the player to try out other puzzles when they get stuck. The current puzzle count is now at 94. The last play test by a good friend of mine lasted 4 and a half hours. So I'm no longer worried about the game being too short!
Tomorrow I'm presenting and demoing the game at a Playcrafting.com event in Boston.
There are still more puzzles to figure out and add, some to tweak based on play testing and some to remove completely. The majority of the work left on the game seems to be polishing art, sound, player movement and adding the story elements. I suspect there are a few months left of work before re-evaluating the state of the project.
I hope to be posting updates more regularly as the art progresses!