1.Correct linear lighting & PBR
2. Deffered Shading
3.Better Shadow maps
4.Soft Shadows and Hard Shadows with PCSS filtering
5.Screen Space Shadows
6.Better Screen Space Reflections
7. Volumetric Lighting
8.Area Lights
9. Physical light units, IES lights.
10.Order Independent Transparency(if possible)
11.Realtime Reflection Probes
12.Better Shaders and a good shader system
13. A Day Night cycle and weather system ( if possible)
14. Local Fog
15.GGX with Metal & Specular
16.Anisotropic GGX
17.Sub-surface scattering with translucency
18.Clear coat shader
19.Double sided shader
20.Good specular occlusion
21.Hair, Eye, Cloth shading models

Correct HDR for GI
Consistency with direct illumination
Soft Shadows from indirect illumination