Unreal is a huge mess. No wonder most games in that engine take years to build from scratch. From what I understand, there needs to be everything rendered like a separate DAZ asset, from the sword to the clothes, every damn thing needs to be rendered like a different body, because the engine needs to use such resources to arrange the scenes every time the game atarts.
Unreal games are unfinished horrid messes around here, either scenes with no story or game mechanics to resembe a game, either large empty spaces with nothing to see, as the assets need countless hours to render separately and then get integrates in the engine one by one.
Where you can build one image and use it for a whole background in RenPy, in Unreal you need to render every object in that place and make it look 3D, because if not, it will look like cardboard.
All the GUI in Unreal is nonexistent and many built in mechanics of RenPy you will need to code from scratch.
Unreal is a huge resource guzzler and unless you find and pack the right supporting DirectX components, players will hit brick walls and fail to run the game as it should.
Up until a few weeks ago, my answer would be "sure, no problem". However, in recent weeks I've been talking to an Unreal developer about the possibility of making the next game in Unreal. I don't know if we manage to pull this off (my currently guess is about 40%) but if the next game is in Unreal, it may be complicated to import from Renpy. Or not. Perhaps it's not too complicated to open a Renpy save file, extract the flags needed and use them in the next game. I don't know yet. But I believe it's reasonable to expect that old saves could be used in the next game regardless of the platform used.
As opposed to Unreal 4+ GB of nothing but game engine fodder, Unity does pack way smaller distros, at least comparing the games we already have around here.
