Premieres December 31, 2024. The new PV is here. Check out the ANN article for additional information. Synopsis from AniList:
In a Holy Grail War, Mages (Masters) and their Heroic Spirits (Servants) fight for the control of the Holy Grail—an omnipotent wish-granting device said to fulfill any desire. Years have passed since the end of the Fifth Holy Grail War in Japan. Now, signs portend the emergence of a new Holy Grail in the western American city of Snowfield. Sure enough, Masters and Servants begin to gather...
A missing Servant class...
Impossible Servant summonings...
A nation shrouded in secrecy...
And a city created as a battleground.
In the face of such irregularities, the Holy Grail War is twisted and driven into the depth of madness. Let the curtain rise on a masquerade of humans and heroes, made to dance upon the stage of a false Holy Grail. This is a Holy Grail War covered in lies.
I think people have managed to get it to run on Android (no official English version was ever released on Mobile but there are good fan translations, all we had until this year on any platform.)
There is also a website that works on mobile and has a playable version of the fan translation hosted and is mostly complete but missing some details. (Edit: there you have to be careful not to slip into the wrong routes though.)
Fun fact about the VN: When Nasu wrote FSN, they originally did not want to include any H-Scenes, but Takeuchi, the artist, thought it wouldn't sell otherwise. This lead to the 2004 release having some legendarily bad (and often memed) H-Scenes in them as Nasu is not really known for writing ero-stuff. Whether or not you want to read those or read any of the remade versions where they replaced the spicy stuff with more tame stuff is up to you.