The game is laggy because it's being rendered in Unity, using polygons and objects instead of "real" voxels for the demo. The demo has tens of thousands of objects in it, which makes Unity chug, but their own engine, they say, is capable of running with millions of voxel blocks without nearly the performance problems the demo has. They're just throwing this out in Unity for the demo because their own engine isn't ready for players to mess around in, yet. (Presumably, the cause of the lack of gameplay video, earlier.) The demo is more "proving we can do it, just give us time and funding."
In fact, speaking of their engine, I was talking to them about the shape of their worlds, and they were talking about how they had experimented with different types of gravity.
The project leader says the current idea of a world is one based
upon this article on a hypothetical cube-shaped planet in real physics. Where gravity still pulls towards the center of the cube, meaning that the cubes seem to slope upwards as you walk along, leading to a world that looks like
this concept art, with central oceans, "mountains" on the edges, and an atmosphere that can't reach the top of the mountains.
I was arguing to him the advantages of a more Mario Galaxy type of approach, with an invisible plane that just change's gravity's direction, especially since it would mean you could have planets that had more Earth-ish geology/worldgen like DF's. (Plus, how cool would it be to sail a ship over the edge of the world, just to have it pivot on its axis 90 degrees, and keep on sailing... in the middle of naval conflict?)
He was talking about how they were testing it, and thought it might cause problems with disorientation. That is, sort of like Portal, what direction is "up" suddenly whipping around the player as they fall getting the devs testing it weirded out. He also was worried that it might seem too "gimmicky" a concept.
For one thing, I responded, I think some strong gimmicks would help the game stand out as more than just a mash-up of existing games trying to find a harmony, but also because it lets you play with DF-style geology. (Including the likes of having igneous extrusive stones in some areas, and sedimentary stones in others, with differences in where you go to mine what.)
Either way, the game is geared towards having a planet built at the start of the game, with a full map and a bunch of civs to interact with, and using a planet as a unit that gets generated when they get up to the point in the game where we actually are leaving the homeworlds. (Which even they say is 2 years of development away.) Hence, more like Terraria or DF, you have a world that has a consistent, logical placement for everything, rather than random patches of biomes like Minecraft has, just because it doesn't have a central plan and makes up everything as it goes. (It seems other civs, however, WILL be made up as you run into them. Or, at least, heavily abstracted when out of view. They want to take cues from games like X3 on things like that, where the game resolves abstracted "turns" for various Out-Of-Sector action instead of real-time every 30 seconds. Splitting when each slice of the universe resolves its turn with a scheduler system keeps the world running smoothly.)
If you hop on their forums or chat, again, there aren't many people there, yet, so it's a good time to be quite influential in an early stage of development.