https://www.kickstarter.com/projects/rustyseas/rusty-seas
It's still being worked on, but there's been some family emergencies and the game is currently getting late-game spoilery content worked on, so it'll probably be a bit before there's much new to show.
That's what I got from the updates in the emails and on the Kickstarter page. Which sounds about right for a game that's only got one main developer on it.
That said I admit I had no idea there was an itch demo at all, and I wonder if AyGee forgot as well, because I'd have thought they'ld have responded to some of these comments themselves. But given the life updates, they may just have been too busy helping with the heart problems.