Pxls.space is an r/place clone that originated from Reddit so there is a chance of users (that once came from Reddit) to move to pxls.space. Reddit plays a much less significant role in pxls.space today but people have been known to go to Reddit hoping to recruit new players.
2018
There were a decent amount of subreddit posts but it is unknown if they actually succeeded or failed. Even if they did succeed, a majority of these factions / subreddits would permanently die forever.
Rust
One of the first original posts was made by user "Pjosip" asking to make a rust logo with around 4 upvotes and 64% upvoted.
https://www.reddit.com/r/playrust/comments/63ek0b/rust_logo_on_httppxlsspace/
Fnaf
Another old post made was by "SpringtrapReturns201." This subreddit post doesn't seem to have lot of influence nor did it actually have a template. One important note is that it contained a rick roll video (as 2nd link) so it's a possibility that the post was made as a joke. No artwork/template was made for this subreddit.
https://www.reddit.com/r/fivenightsatfreddys/comments/63awhj/pxlsspace_new_fnaf_monument/
Blue Corner
This is considered the first and most old subreddit post to be posted in a previous r/place faction, The Blue Corner.
https://www.reddit.com/r/TheBlueCorner/comments/6484cy/pxlsspace_blue_corner/
It is unknown if this plan worked but TheBlueCorner (from r/place) did end up moving to pxls.space.
Osu
This would be one of the most upvoted posts within the year of 2018 with over 200 upvotes and 95% upvoted.
https://www.reddit.com/r/osugame/comments/656juj/httppxlsspace_and_we_have_our_logo_nice/