I think Zone's problem is simple: Its gameplay is too similar to Era's. There are very few reasons to play Zone that aren't already covered by Era. The systems, the content, and even some of the graphics are identical. Players left Classic for Era because Era offered something new. But Zone? Zone has never had much that Era didn't offer better versions of.

Sure, Zone has a few neat systems like the bomberman spar and missions that I don't think are offered on Classic or Era, but the foundation of the server is basically Era with "updated" graphics. Current development progress does not seem to be straying very far from this, either, so I think it will need some overhauling before it will succeed.

I personally think Zone should go for the whole Sci-Fi / space station type deal.