I'm going to guess it won't run too well on a Pi3B+ even, but...
Contact EPIC Games if you're looking for a version that runs on the Pi3B or Pi3b+, though really, I'd opt for a different brand SBC for this idea. Something with a more powerful GPU, as Jamesh mentions.
I would suggest contacting EPIC Games and see if they can compile a Rapberry Pi version from their ARM version because unless the source is available, you won't be getting it on a Pi and I'm pretty sure EPIC Games won't be giving out the source code.
The chances of this actually happening are slim to non-existent.
Stephen Hawking, rest in peace.
8 January 1942 – 14 March 2018