Steins;Gate 0

Both of these anime definitely has a lot of similarities, especially the characters of Okabe and Subaru. Both act outrageous to amuse the people around them and go through a lot of mental stress trying to save the ones they love. It's quite obvious Steins;Gate fleshed out its time travel element more and in case of Re Zero it's time travel with supernatural aspect. Both of these characters shows a similar type of ability - Subaru every time returns from death in a specific point of time functioning similar to Okabes time leap. Both deal with this despair feeling, and have contrived stories. You can take Re Zero as Steins Gate 3 with no time travel scientific mechanism but with a lot of sufferings and I mean a lot.  read more 

The plot is very sad and exciting, exactly like S; G, also the "return to the past" mechanics reappears present in -Steins; Gate 0 El. Psy. Congroo. 

Two noteworthy works of art, in both there is a protagonist who has to do with great complex psychologists to deal with in an attempt to keep the world they care about more "unaltered". In both the time plays a fundamental role. 

both have similarities in terms of storyline and character, in which the main character has an bad fate and is very suffering from the person he loves being killed. 

So, essentially, the similarity between these is in protagonists. Okabe's behaviour and action patterns somewhat correlate with such of Emiya Kiritsugu. Also, both of them go through lots of crap to protect their loved ones that makes a huge impact on their minds.