The Fate/Series comprises of different iterations of the same story, parallel worlds with different timelines, same worlds at different times (centuries or millennia apart), spinoffs, and some are barely related by the series...
The original anime release order for the series. Note this is different than the chronological order. This is generally how you'd it watch if you watched it as it aired. There's also novel release order which is also viable and...
SYD does not have much of an overarching plot, but there is still an intended watch order to get the most out of the series. Otherwise some scenes won't make sense, and you will miss out on character development.
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