Ray's going to release yet another Cthulhu-girl dating sim soon:
https://www.dlsite.com/maniax/announce/=/product_id/RJ01315626.html/?locale=en_US

From what I've read he was dissatisfied with how Fia from Determinable Unstable turned out and made this as a result.
Seems she's actually a Cthulhu this time - with magic and shit.
But yeah, it's going to be very much like Determinable Unstable.