I have seen those, most of them seem abandoned.

Though so is Impact (well, unmaintained) and its plugin ecosystem (the website died and the plugins it hosted are lost), so it's more or less something you have to be comfortable with if you choose to use Impact in 2018.

Excited to see it open source now, of course. Great opportunity for a community to slowly redevelop and rebuild what once was.

I used Impact as recently as two years ago despite these issues and was able to make a networked game. The code is easy to work with and understand. And I used one of the Node wrappers to get the editor working without PHP.