Ankhrono It's really interesting to read your thoughts on the project as a whole and its scope, so thanks for sharing the insight.
I've mentioned previously that I like your art style as there's a lot of charm to it. The themes and fetishes that you work with are very pleasing which I really appreciate, and as an artist you clearly have talent and definitely garnered fans who enjoy these niche themes. What I'm saying is that as far as the art goes, Mira Co is great and unique.
But as far as game design and gameplay goes, Mira Co does seem a bit "aimless" at the moment, perhaps lacking a more clearer long term vision. The game does feel like you're coming up with gameplay and story progression as you go along; it feels like every section is patched together instead of being part of a concise whole. It's not necessarily bad mind you but it does make for quite a "meandering" experience, so to speak. For now, I play it more like a "gallery" of sorts enjoying seeing the girls in various peril situations as opposed to playing and enjoying it as a proper overarching story.
It is as you said after all; it started as a small hobby which kinda snowballed from there so it's perfectly understandable why it is so because there wasn't an initial design plan and you just went along working on it little by little. Also the game is still being developed so maybe it's too early to bother with that because once you're closer to completion you would go back and tie everything up together into a more concise experience anyways.
So we finally reach the question that you proposed: what should you do moving forward after 0.5?
On the one hand, you could continue working on Mira Co, adding more content at your own pace and eventually tie up all of the game's sections and areas into a more continuous game experience. Alternatively you could retire the project and if you feel like it already gave you enough experience, you could start a new one where you would have a design plan from the start to create a better and more focused project.
It's a tough decision but it's ultimately up to you. I personally would be okay either way: I like the main trio of characters as well as some side characters, so I definitely would like to see more of them and their stories being ultimately fleshed out. But I'm also confident that any new project that you started would be right up my alley, specially if starting fresh would enable you to create a better game... so yeah wherever you decide to go forward, as long as you're happy to work on something that you're inspired and not burned out, I'll be following it.