Hello,
That is indeed 100% poor game design that ignores basic rules of
development for VR and nothing to do with the Unreal engine itself. They
have obviously used billboards, flat "leaves" and 2D overlays that work
ok on a monitor but not in VR. That is what the stock foliage and tree
libraries that both Unity and Unreal engines use to lower the resource
usage. It is visible in the screenshots already. A "VR compatible"
foliage would require a lot more polygonal complexity and likely redoing
the graphic assets for the game.
The reason for it is that that game has not been developed for VR - it
is a normal desktop game that got a "VR patch" to support an HMD later,
so no surprise that it shows. Turning on the HMD support in Unreal/Unity
is not enough for a game to work well in VR, unfortunately - and many
studios *still* ignore this.
For a game to really work well in VR it needs to be designed for it from
start. It is kinda like with the 3D movies - Avatar looked great,
because it was shot in 3D outright. The following 3D films were often
only converted from the original 2D to 3D - and it sucked bad, putting
people off the entire concept.
Regards,
Jan