we are betatesting it and fixing bugs. It will be released within a couple of days. There is a lot of hidden work we are doing for porting our actual engine to nebula4. Nebula3 will not be discontinued, it will be the best tool for individual instances/presets, while nebula4 will be focused on multi-instance load, the rack paradigm, routing, custom skins addressed to individual nebula categories and so on. For this reason they share almost all the source code.