a list of all rooms, recently active rooms first
Test room for https://meta.stackexchange.com/questions/325096/why-can-only-some-child-meta-sites-host-chat-rooms-is-there-any-way-to-bypass-t
Discussion forum for https://3dprinting.stackexchange.com/
Product Recommendations / discussion. This room has different standards than the main Q&A site. Open discussion & opinions are welcome here; however, please do not post questions here that are on-topic for the main site.
For playing the game Contact, where one person tries to "defend" a word against being guessed and others try to "attack". See https://puzzling.meta.stackexchange.com/a/5992 for more info. Bot source code: https://github.com/GentlePurpleRain/Lens
For functional analysis, measure theory, and related areas. MathJax in chat: http://www.math.ucla.edu/~robjohn/math/mathjax.html
Related to https://chat.stackexchange.com/rooms/64952/conversation/problems-in-posts-and-comments-added-by-automated-adding-of-begingroup-endgrou
Discussion related to the use of algorithms and programs to visualise real numbers and other sets. Number theoretic discussion based on the graphical interpretation are encouraged, so as relevant proofs
Any discussion on Probability and Statistics.For rendering LaTeX math.ucla.edu/~robjohn/math/mathjax.html
Anything related to set theory. For instructions how to render MathJax(TeX) in chat see http://meta.math.stackexchange.com/a/3297
This room is meant for all basic mathematical discussion, including basic logical reasoning, simple properties about natural/rational/real/complex numbers, induction/recursion, elementary combinatorics, synthetic geometry, ...
For any discussion concerning linear, abstract or even elementary algebra
For feedback/discussion/requests of Close/Reopen/Undelete/Delete/Edit for questions and answers on Math SE (for Math Meta stuff go to https://chat.stackexchange.com/rooms/64952/math-meta-chat instead)
General discussion for http://boardgames.stackexchange.com. Chat about board games, card games, or the site itself.
For informal chat with the site moderators about moderation, spam, troublesome users and other issues you need ♦ input on.
General discussion about http://skeptics.stackexchange.com/
A room for anyone interested in homotopy theory, or any nearby fields (e.g. category theory, algebraic geometry). To activate chatjax in this room go to http://meta.math.stackexchange.com/questions/1088/should-chat-have-tex-support/3297#3297
General discussion for http://history.stackexchange.com. For urgent issues, idle chatter, and everything in between. Reference requests welcome.
For playing the game Spyfall. Join/create games here: http://spyfall.crabhat.com More info here: https://puzzling.meta.stackexchange.com/a/5991