The preferred way to create facial animations is to add face shape drivers to the armature. In this way you can access the face shapes also when the character is linked into another blend file. However, it appears that drivers don’t work with the BGE, and they will definitely not work if you export the animation outside of Blender.
To fix this problem, I added a way to transfer face animations directly to the mesh shapekeys. Or actually, two ways;
- On import, select Face Shapes but unselect Face Shape Drivers. The buttons in the Visemes panel now affect the shapekeys directly, rather than rig properties. So you can use the visemes buttons to create a shapekey animation directly.
- Select both Face Shapes and Face Shape Drivers, and create a face animation in the old way. Before using the animation in the BGE (or exporting it to some other app), press Bake Face Animations in the Visemes panel. This button transfers all face animations to the mesh shapekeys and removes the drivers and the rig properties.
To access this feature, download the unstable version from https://bitbucket.org/Diffeomorphic/mhx2-makehuman-exchange/downloads.