Hi, I am a senior game developer.
I have plenty of experience in developing a game in unreal engine 4.
So, I can complete your world with high quality in unreal engine 4.
Please check out part of my projects in UE4.
https://www.freelancer.com/projects/unity-3d/Oculus-Room-Unreal/
https://www.freelancer.com/projects/Android/Unreal-Game-Development/
https://www.freelancer.com/projects/Game-Design/Build-game-using-unreal-engine/
https://www.freelancer.com/projects/Android/Fix-unreal-project/
...
If you want a good result, Please feel free to contact me anytime.
Best Regards.