How is the performance currently? Does a world of that size allow for a playable framerate? Anything over 10 or so FPS would probably be enough, as long as it's consistent.
It runs okay- it's definitely playable. But it still needs ongoing work. I'm actually redrawing the entire world each time anything changes, with culling of course, but in order to have a bigger world or faster game in general I definitely need to figure out a different way to do that. I'm also recalculating the entire world light each time you place or break a block, and I'll have to optimize that too for sure.
If you look at the screenshots, any time my selection box is hovering over a spot for a while before placing a torch, that entire time is actually being spent calculating new light. It looks like I'm idle, but the program definitely isn't.
As for animated blocks (such as fire), those are still very much test features, and they definitely slow the game down.