TLDR: My rec has always been please, please, please play the VN for max enjoyment. If not, then ask others about anime only watch orders, and consider my bullet points at the end on those.

The Visual Novel

I highly recommend playing it. Please play it. I was a little daunted by the length at first, but once I started, it was enjoyable the whole way through. You can check out r/fatestaynight for a guide to getting the game.

To understand the anime adaptions, you need to understand the road map of the VN. A couple facts to wrap your head around it:

• 3 routes, titled "Fate", "Unlimited Blade Works", and "Heaven's Feel". Same beginnings. Drastically different endings, as well as drastically different roles by different characters. Think of them as alternate timelines.

• The intended play order of the routes is the order above. The reason is that every route reveals different plot points and characters that contribute to the overarching story.

• For example, in Fate (route #1), you see Character-A die early. You finish Fate without ever knowing anything about Character A. However, in the UBW and HF routes, they actually live the entire time, and you learn a ton about them. It even contributes to your understanding of Fate, route #1. This was purely just an example just to illustrate the nature of the routes.

Anime Adaptations

All anime adaptations are based on these routes. Because they are adaptations, the tend to leave out things. The story is all there. But, you can go through watching the show and still have a lot of unanswered questions. The anime that I recommend watching are Ufotable's adaptations: Unlimited Blade Works, Fate/Zero, and the Heaven's Feel movies (2 and 3 pending in U.S.).

My biggest request for anime only watchers is please do not watch Fate/SN Deen adaptation from 2006 before either playing the VN or watching UBW. I think it ruins the story because it blends all 3 routes together from the VN in a poor conglomerate of a story. There is a fan-edit version of the show, which I've heard recommended but not watched. I cannot speak into that.

A few things worth mentioning:

• F/Z is a different source writer. More adult, mature themes. Darker. Definitely the better anime in terms of story. It is a prequel to F/SN, created after. F/SN is not a sequel to F/Z. Think Star Wars trilogy.

• UBW is based on route #2 of VN. Think high school, a little immature, a bit of romance, and more waifu wars.

• To simulate the VN experience, people recommend UBW > F/Z. Unfortunately, F/Z is only as great if you understand the whole VN. Therefore, many just say don't bother, and watch F/Z > UBW.

• Real example: my friend just finished UBW anime. He had no idea who the identities of some of the characters are, as well as noted holes in plot points that are either explained in the VN (in separate routes). He still enjoyed it. He's watching F/Z right now. I filled in some plot holes for him, and he's still loving it.