Heroes from legend are brought into modern day and meet up. Fate is a large series with many heroes looking back at their legends, Zero is the better part to be animated so far. Re Creators takes some fictional characters it made up and has them meet their creators and meet other genres.
Both of these series have the same director and they are both anime where powerful figures appear in the real world and fight each other. Fate Zero involves historical figures fighting for the Holy Grail while Re:Creators involves characters from various forms of popular media (anime/light novels/video games) fighting over the fate of the consumer world and the people who created them.
Both have main characters crossing worlds and being confused about it.
Re:Creators has a really original premise: fantasy chars appear in modern Tokyo, not knowing they were watched by Otaku as anime/game characters, and now have an opportunity to find their writers and animators and beat them to a pulp if they want; one young otaku gets an accidental prime spot as an improvised "Japanese host" for the girls (after some sketchy events ofc), then a plot appears and there are fights between those characters everywhere!
Gate has the Japanese SDF cross a gate to a fantasy world, face its armies and after that goof around trying to get some mining done. The whole show centers around a small SDF unit joined by a few cute fantasy characters with a lot of politics in the background and a lot of awesome and entertaining army muscle flexing, as they're orders of magnitude better than any fantasy army. It's worth noting that the show spends a few episodes on a group tour back to Japan, so it's not only one way. read more
In both stories the anime/other world bacomes reality. The people from the anime/other world as well are the people form the real word fight for their beliefs. Both male MCs like very much anime/manga/light novels and also like to come in contact with the people for the anime/other world.
Both have the same plot where powerful beings from another dimension comes to another world where they have established themselves as the superior ones, however , in Gate it involves humans coming in from a portal that connects to their world to the world of fantasy , in Re:Creators in the other hand it was a complete reversal, where it involves, the works of man coming to life and establishing themselves into the real world.
Both series are about... characters from different universes united in a world, where they fight each other. The only difference is that one is more darker, gory and includes real people that once existed on this planet such as Nobunaga Oda and Joan of Arc, the other has fictional characters from anime series and games.
-Similar setting with dark theme.
-Both have characters who have supernatural powers (Celty in Durarara!!, The "fictional" characters in Re:Creators).
-Main Protagonist are kind of similar: they looked like a normal high school boy, but they actually hiding something that will make a change in the story.
-Both have a lot of dialogues. If you like dialogues in anime, then you'll probably like both anime.
-IMO, Magane is like the female version of Izaya lol.
Both have characters that are summon to the real world. The difference is: Fate has historical characters summon to fight against each other in a kind of war, on the other hand, in ReCreators characters from anime, manga, light novel and games are summon to the real world and they don't know why exactly. Both of them have good action scenes. Fate is a more serious one, and ReCreators have a little of comedy in it.
A group of strong characters from different places gathered in one place. They're not familiar with each other, but they have the same goal (to defeat the Demon god in Rokka no Yuusha/to found the creators in Re:Creators). But, instead of achieving their goal, they just fight each other to prove that they're on the right side.