Hi,
We’re trying to achieve a low-poly, flat-shaded look in our game.
For the meshes we can do that, by not exporting the smoothing groups in any 3D software. We still haven’t found a way to apply this kind of shading in the unreal 4 editor. It would be very nice if we could use the built-in landscape editor for our environment though.
Thank you for any possible advice 
I’d like to know too, anyone know of any good shaders also that modernize flat shading but keep the retro flatshaded look?
I’d also be interested in the answer to this. Using the landscape system with a flat-shaded material would be awesome!
Oh, looks like someone found the solution already:
Basically you ignore the interpolated normals coming into the pixel shader and calculate it based on world position, right?
Yeah, that’s what that solution is doing. The thread is on exactly this topic, so it’s worth reading through! I just tried out this solution: https://forums.unrealengine.com/attachment.php?attachmentid=766&stc=1 and it worked like a charm.