Some games are incompatible with Sclender but require more resources than Virtual Box can give you. Games which require more than 256mb VRAM will not run in Virtual Box, nor will games which require DirectX 12. For these situations you need an alternative approach.
Note: these solutions require either VMWare Player or Hyper-V.
GPU-Partitioning (GPU-P) is the method currently recommended by Microsoft. CPU-Partitioning allows GPU resources (meaning CPU cycles and VRAM) to be distributed between several VM running at once (or to give all resources to a single VM). It is recommended to use tooling software to setup GPU-P, such as Easy-GPU-PV
Discrete Device Assignment is a solution offered in Windows Server 2019. It allows you to dedicate individual GPUs to one VM's exclusive use for as long as it is running. However this also means that the operating system running the VM cannot itself use the GPU. Not all GPUs support Direct Device Assignment (typically only server-farm GPUs like GTX Titan series).
- More information: Discrete Device Assignment at MSDN
- Windows 10 versions before 2019 offer a feature called RemoteFX which can allow a virtualized GPU to access up to 1GB VRAM.