Reddit and Twitter were big things for me, I announced the initial release on the Rocket League subreddit[1] and then announced updates whenever they were released[2][3][4][5][6][7][8]. I automated daily posts to reddit and Twitter[9] for the "match of the day" (calculated based on a variety of factors). I engaged heavily in the community on Twitter, other fan sites and got my name out there. I gave away the extra (paid-for) features to the top teams to get them using it. I added support for features which users asked for.

One of the biggest sources of traffic for me now are the Rocket League analysis / training subreddits[10]. It's become _the_ location to upload your replays if you want to share them with other people. Making it easy to share (no account required) was a big part of this.

[1]: https://www.reddit.com/r/RocketLeague/comments/3et5yx/after_...

[2]: https://www.reddit.com/r/RocketLeague/comments/4f3jq2/rocket...

[3]: https://www.reddit.com/r/RocketLeague/comments/4d1kpe/rocket...

[4]: https://www.reddit.com/r/RocketLeague/comments/4a9s44/rocket...

[5]: https://www.reddit.com/r/RocketLeague/comments/44xp8j/rocket...

[6]: https://www.reddit.com/r/RocketLeague/comments/3yws8d/rocket...

[7]: https://www.reddit.com/r/RocketLeague/comments/3pra3u/rocket...

[8]: https://www.reddit.com/r/RocketLeague/comments/3gtulm/rocket...

[9]: https://twitter.com/RLReplays

[10]: https://www.reddit.com/r/RocketLeagueAnalysis/