The RISK: Global Domination Community has organized itself on various Discord servers.
Here are some of the largest ones:

Official Discord Community with 100,000+ members:

Official Facebook Community

RISK 4 Ever - Playground of the champions. For those who want to play Grandmasters:

Reddit: All things Risk. Not just this game

These links are being provided as a convenience and for informational purposes only; they do not constitute an endorsement or an approval by SMG. SMG bears no responsibility for the accuracy, legality or content of the external site or for that of subsequent links.