For this, we targeted Reddit (specifically the IndieGaming subreddit), Gamejolt, and Itch.io.

Reddit
We requested a specific style of video from the developers - a run through of a level (6 minutes long) where the camera followed a set path. This video was then broken down into shorter clips of 30 seconds which we then used as the post.

We then took on an excited tone (intentionally) to showcase what we are working on.

The post was a huge success (550 upvotes is great) and it helped us establish a presence in the subreddit. In order to keep things friendly, we limited ourselves to post 1 time a week (as every subreddit has their own rules on self promotion) and on the other days, we would use the account to engage with the other posts.

After this video was seen to be popular, we also created different posts (same video) on other subreddits such as r/Unity3D, r/IndieDev to further generate community awareness - both were met positively as well.

To keep the momentum going, we then set up pages on: Itch.io and Gamejolt.

To act as community hubs and to give us a position to tap into their communities. What's more, both platforms are also very popular in the Indie-Gaming community, so it provided us with early talking points when setting up Twitter.

Special attention was given to both page's layout as the page style is very important to the platforms.

What is important to note is that these three platforms are intended to be used throughout the game's development as we do not believe in creating a community page, only to abandon it to dust later.

Remaining active, providing updates, and engaging is the key to sustainable community growth.