what about the other grail wars? like Fate/Hollow? and fate grand order?
and what are those anyways?
Fate/Hollow Ataraxia is a "sequel" Visual Novel to Fate/Stay Night.
It's actually just kinda like official fanfic, it follows no routes, yet at the same time follows all routes (it's complicated) it's just pure fanservice where all humans and servants are alive.
Fate/Grand Order is a japan-only online game where you get to summon many Servants. The story is supposedly good, but the gameplay is just awful. And it's in japanese so I don't recommend it.
Fate/Prototype is an early draft of Fate/Stay Night turned into a Light Novel series.
Fate/Apocrypha is kinda like an alternate universe. It's a Light Novel about a war between two teams of seven Servants each.
Fate/Strange Fake is a distant sequel to Fate/Stay Night, haven't read much but it's apparently about some North American mages trying to copy the Fuyuki Holy Grail.
Fate/Extra is another alternate universe where the world's Mana dried up before the events of Fate/Zero and Fate/Stay Night occurred. It takes place on a Holy Grail War inside the Moon. It's a RPG for PSP, you can choose between 3 Servants, Saber, Archer and Caster.
Fate/Kaleid Liner Prisma Illya is a magical girl alternate universe anime/manga focused around Illya.
Definitely check them out if you like Fate/Stay Night and Fate/Zero, though IMO they don't surpass them in quality xD