Some studios are using them as base characters, mostly using the LOD setup to get them to work in an efficient way considering performances.
You could also do that, but you need to understand the under the hood setup, otherwise you have no idea what’s going on.
Thing is, is it critical for you to use a MetaHuman? or better yet, what are the features that you would like to have from a MetaHuman onyour character?
Because after you set your own rules for characters, you can simply get what you need from the available resources.
For example, you don’t need the super shiny over complex facial rig, but you just want a simple blend shape based rig, and you eventually want to use also lipsync?
You can extract facial shapes in Maya literally creating the pose, duplicate the face and delete its history, call it with a proper name, that’s it.
Do you need all the various PBR maps from the facial rig? or you just want diffuse/normal?
They’re already available for you to use, in case you can just use a good old 512/1024 map if you don’t need anything super detailed.
Do you need proper body deformation? if yes, the current skeleton works fine, otherwise just delete all the corrective joints and update the skinning on the mesh.
Worried about too many characters on screen? Use Vertex Animation, within the Matrix demo they show a setup where they switch in realtime between skeletal characters and Vertex Animation characters.
I said before, you can use a MetaHuman as a game character…but do you really need one?