Yeah, FGO is a great game, I have a friend who plays it, he always brags about the fact that he has Astolfo in his team, and I am familiar with this universe only from the anime.

Well. Arknights got an anime adaptation. As well as manga. It's mobile gacha game. But got a good plot (this is why anime and manga adaptation exist). Manga - Arknights: OPERATORS! (Ongoing). Anime - Arknights: Reimei Zensou (1 season). If you want to try game, I would recommend playing on emulator, like bluestacks (recently it got 120 fps mode support on this game). Gacha games are often grinding. So on pc it's easier to play. Feel free to ask me any question about this game.