Never really got Koikatu to work for some reason, and eventually just gave up on it. But other than Koikatu, which I can't really comment on, the last game I actually thought was decent from Illusion was Articifical Academy 2 back in 2014, and kind of Sexy Beach Premium Resort the year after, and before that Love Girl was the last good one, two years prior to Artifical Academy 2, and that's with several releases inbetween the ones mentioned, and after Premium Resort.
I used to get really damn excited as soon as Illusion Games name popped up, but, well, the meme cycle of excitement into disappointment that's been coupled with them for over half a decade has settled a bit too hard for me. Still very curious, and I hope that this one will finally live up to the golden Illusion games of yore, but I kind of doubt it.