Seems just as finished a product as it can be. If there are people who want voices in it then it's up to you if it fits your vision. From what you brought up as examples of where you could take the serries I would suggest mixing it up. One game a little of this and a the next a little something else. I personaly don't mind this format at all and I've been glad to put my thought into it to solve the puzzles set forward in the game. They're not to hard but it takes some creative thinking and not so much where it would be beyond most viewers to get through with a little extra effort or thought.
I would warn you though. If you consider branching away from the format you have into another be sure of the end product. It may not meet up with everyone's expectations.
Knights
Your new game series is quite excellent as a game and as a story.
My only gripe, is when I mess up on a level, I don't want to start the entire game over to get back to that part. Some checkpoints would be nice, or maybe a restart button.
Keep up the good work!
Zeebarf
I hear ya! I'll add checkpoints into chapter 2. Thanks for the support!