A lot of people have characterized both The Moon Sliver and The Music Machine as "walking simulators." Not always disparagingly, either. I've often referred to them as such too, if for no other reason than it gives people a pretty clear idea of what they're like: lots of exploring and text, not so much in terms of "gameplay."
I've really never thought of myself as a "walking simulator" developer, though. The Moon Sliver was an experiment in using non-traditional gameplay to tell a story (i.e, non-linear exploration mixed with a non-linear story), and The Music Machine was an attempt to bring actual player action into the mix.
My approach to gameplay and storytelling, since Fingerbones, comes not from a desire to minimize gameplay, but rather from a struggle to provide meaningful interaction that doesn't trivialize the story by being overly "gamey." Don't get me wrong, there are many situations where a videogame can be a shameless videogame, and be all the better for it. Even when dealing with serious subjects or worlds. But for my purposes--for the sort of experiences I want to provide right now, and the stories I want to tell--I find the tried-and-true gameplay models to be inadaquate at best, and severely damaging at worst.
For the past year and a half, I've been experimenting with horror games that focus on atmosphere, reserved pacing, and narration rather than simulated danger. That may not always be the case, but for now, it is. So for the past year and a half, I've done a lot of thinking about what you do in a horror game, where you aren't shooting or hiding from enemies.
Puzzles are the most obvious solution. That's what I went with in Fingerbones, although I tried to make them a little more than just roadblocks between notes. For my part, I've always loved simply being free to explore, so The Moon Sliver was focused more on that. The Music Machine was similar, albeit with some major improvements in the storytelling logic (dialogue instead of mysterious text) and more actual interaction with the environment and some ability for the player to impact the story.
I've also wanted to try out branching dialogue and character interaction as the primary gameplay mechanic in a horror game. Actually, the original designs for both The Moon Sliver and The Music Machine had actual dialogue systems, but they were cut for various reasons. Some of it was streamlining and refining the design, but some of it was also because... well, writing is hard. And don't take that as a cop-out. Although I'm pretty satisfied with how The Moon Sliver turned out, I had a lot of trouble with the story throughout development, and maybe 40% of it was entirely re-written about two weeks before release. The Music Machine went a little smoother, but juggling all the story threads, themes, conversations, and even the small amount of player agency was already quite a task, even without throwing dialogue trees into the mix. Even without time constraints, there's still a limit to the amount of stuff one person can juggle, without it all crashing down.
That said, some day soon I'd like to do something more focused on interactive dialogue. I'ver certainly got plenty of ideas for it, and I think I could deliver a really unique horror experience.
So let's talk about my next game. It has a name, but I'm not ready to announce it yet, because I want to make sure I'm happy with it. Overall narrative complexity has been scaled back a lot from The Music Machine. It's going to be a lot more like Fingerbones, albeit with more of a psychological twist this time around. It's also going to be much smaller, in terms of raw real estate. There are only two main "rooms" in the whole game, with other areas serving as momentary vingettes.
Gameplay-wise, there's a much greater focus on puzzles than in either The Moon Sliver or The Music Machine. Possibly even more than Fingerbones. The "big idea" is that there are a lot of different tools at your disposal. Some are useful, others aren't, all of them can be picked up and used. Some puzzles will have multiple solutions. Maybe you can unscrew something with a screwdriver, or hit something else with a hammer. Stuff like that. The idea is to get the player actually thinking about how they would solve the situation at hand with the tools at hand, rather than just randomly clicking.
We'll see how it works out. Puzzle design common sense dictates that you can't have too many possible solutions, otherwise it ceases to be a puzzle and becomes a "use anything on anything"-zzle. And, since it's me designing the game, don't expect to have the gimmick adorned with blinking lights and shoved in your face. It's just a different way I'm thinking about puzzles, that will hopefully make them seem less like the glorified roadblocks they generally are.
Whew. That's a lot of text. So, in conclusion, ADHD medication might be good for me after all, and telling interactive stories is hard.