The Toolsmiths gamedev tools
If you work on game development tools (or are a student/enthusiast) you can get an invite by direct messaging your email address to @thetoolsmiths. If DMs aren’t open poke the account first and it will follow you.
Part of the online community is also from the IGDA Tools SIG. That organization is dormant at the moment, but in the past they organized a lot of blog content. That content is archived here.