https://worldbuilding.stackexchange.com/ https://worldbuilding.stackexchange.com/ is also a great community, with great discussions. Part science, part fantasy.

https://worldbuilding.stackexchange.com/ https://worldbuilding.stackexchange.com/ is also a great community, with great discussions. Part science, part fantasy. People tedn to post long fun answers that remind me of XKCD's What If? series.