Hiyoku Renri no Darling is a "filler sequel" to steins;gate. It is for Psp, and as far as I know, this image is from Hiyoku.
I still don't know if a english patch has been released, but it is more about Okarin relationships than time travel.

Also, the anime was okay, but the Visual Novel is much more thrilling, you can take alternate routes and end with any other girl(even Rukako girl mode).
Main differences:
-Okarin's thoughts are occulted in the anime, in the VN he is much more paranoic and Mayushi isn't that much of an airhead(in the anime they don't explain some of her babblings that look nonsensical at first, but she is still an airhead, don't worry).

-Routes and flags! Take any girl you want, and change the course of the history! I don't have to say that a LOT of canon information doesn't appear in the anime, like Rukako having a sister that is a tomboy, references of Chaos;Head, Fayris have mind reading abilities and many others.

-Quality, the animation isn't very good, but in the VN, the artist of every character and image is f**** Huke! And I didn't even mention that every single speak is spoken by fine Voice Actors.

-The story have much more feels in the VN, imagine this: you took place of okabe and you are about to erase <put a girl name here> memories, you know that if you take too long, you will desist the idea of erasing her memories, but while your finger is on the send button, she is crying at your side,holding your arm, begging you to not forget her, because she will try to not forget you, even though she knows it is impossible, and suddenly, you press the button, her cries goes mute, your vision fades, and finally you wake up some days before being the only person in the world that knows how she was in that other dimension. You get that hollow sensation and a chill down your spine as you remember that every girl you knew changed the past, and you had to erase their memories too.

-The only advantage that the anime has is the episode 25, because that part of the story was made after the VN debut. The filler mangas have a lot of extra canon stuff too, since they are perspectives from different characters.