Interestingly, they've decided against putting it out as part of the Early Access release, but will instead hold it back for the full launch.

Success in Early Access has convinced the developers to make a more ambitious campaign than they'd originally envisioned-'like a new full game with 40-50 hours of content'-but of course that means more time is required to pull it all together. Speaking of campaigns, They Are Billions' is still in the works, but the plan has been changed somewhat. Success in Early Access has convinced the developers to make a more ambitious campaign

An option to create a campaign-like series of levels that must be played in order is coming, to ensure players are 'following the levels and the narrative in the order decided by the designer,' and an option to enable branching stories through some kind of persistent state is also on the table, although that's not carved in stone-the developers are currently 'considering' it. After that, load up the website above and press the 'Load Save File' button, and then browse to 'Documents' / 'My Games' / 'They Are Billions' / 'Saves' and then select your '.zxsav' file. The developers will continue to add 'more features, assets, and interesting new elements' to the editor, including interactive and ornamental assets, and of particular note, the ability to mod game rules. You need an existing 'They Are Billions' save game, so fire the game up, and create one if you havent already.

They are billions map editor