Game Dev League
One of the largest game development communities on Discord, offering channels for various game engines, design discussions, and art disciplines.
How to join
This community is open to join. Head to their site to become a member.
Features
Related communities

r/gamedesign
172,000 membersFor topics related to the design of games for interactive entertainment systems - video games, board games, tabletop RPGs, or any other type. /r/GameDesign is not a subreddit about general game development, nor is it a programming subreddit. This is a place to talk about Game Design and what it entails. Use this community to network, discuss crafting rulesets and general game design, and share game design tips with other game designers. Designers of all experience levels are welcome!

r/IndieDev
112,000 membersThis is the place for indie devs and gamers to share anything, be it game development, their favorite games or just cool images, GIFs and music from an indie game in a casual community-run environment. If you're an indie gamer, this place welcomes you too! After all, every gamer is a potential indie developer!