Building the Neighborhood
You have to build out platforms before you can build a community.
You need to build a community before you launch your game! How many times have you heard/seen/read this advice? What it usually neglects to mention is something I call building the neighborhood. Where a lot of devs fail in community building is setting up platforms and strategizing content to keep community members engaged. In other words, you can’t just attract interested people and expect them to keep track of your progress. You have to give them ways to interact with development and stay top of mind.
Email List: An oldie but a goodie. Get emails from interested people. Send out quarterly or monthly email updates. Keep it short and sweet. Get your email list hyped for Alpha, Beta and launch.
Twitter: Encourage people to follow your twitter. Post demos, development updates and random musings on the development process.
Discord: Use Discord for your most involved community members. Consider building your own bots to add meta-games, competitions and contests to your discord server. Only use discord if you are sure you can bring in at least 100 active users. Otherwise it won’t be worth the effort.
Twitch: Stream development days to give people an inside look. Stream demos of working builds so they can see progress.