I'm not a Minecraft fan as I suffer from bad motion sickness with 1st person games, and the bouncy bouncy of MineCraft was the worst. I couldn't even watch my kids play for more than a minute without having to leave the room.
But that's my physical issue, no the concept's. Still, MineCraft was always too grindy for me. Way back when social was a new thing, I was a Second Life player (although briefly. I can't remember why I stopped playing - maybe there was a cost involved?). I loved their idea of player created content with both player created design (people ran things like clothes shops where they created the actual clothes) and player generated content (you could building working machines/vehicles/scripted actions. I had started designing my own "pets" which had both a collectible perspective, as you could get them in unique styles, and also frankenstein your own custom style, plus they were also a Handyman, designed to provide utilitarian functionality for working int eh work, sort of like a butler.
From an originality point of view, I think voxel engines are too ingrained into culture to be anything more than "minecraft clones" these days, plus I'm yet to see a voxel engine that doesn't suffer performance issues in large worlds. I like your idea of a Tron aesthetic (as a hug Tron fan) although it could run the risk of being too retro if not given a modern take. What that would be I'm not too sure.