this one was iirc originally announced for PC aswell ... and its ArcSys ... so most liukely random day in random month out of nowhere
This one is very weird. This wasn't actually announced, as far as I can see, to PC.
What was announced was a similar Japanese collection (Kunio-kun: The World Classics Collection), that was announced for release on Steam in Japan (no news about an international release).
But then, the collection launched exclusively on another PC platform (DMM.com GAMES PC), and didn't launch on Steam at all.
Since then, ArcSys has been ignoring all questions about a PC release.
First Darius Cozmic Collection was developed by M2 so it's probably not happening at all (and the second one will probably share the same fate).
I really don't know what the deal is with M2.
They keep saying they want to release their arcade ports on Steam (and have worked on a few Visual Novels that are available on Steam), but then, because of some "performance issues" in getting the games to run well on PC, which they say they still haven't been able to resolve, nothing ever materializes.
The titles I listed, besides the DD/Kunio collection, have another handicap: Taito really doesn't care about releasing their titles on PC.
The few they have released, they slapped an online requirement (due to piracy concerns), and the titles were pretty much abandoned without updates or new DLCs.
I mean, the last time I checked Groove Coaster didn't even have proper controller support (you had to run the game in BPM, and manually activate Steam's controller support, which would then cause problems with a few other games).