Learn how to use soft bodies in the game engine.
Soft bodies in BGE are so limited and finicky, some game developers have given up on them and have resorted to simulating them with chains of Rigid Body objects held together with Rigid Body Joint constraints. We can't be too surprised; after all, BGE is based on Rigid Body physics. Nevertheless, as this tutorial will show you, Soft Bodies can be used in BGE quite well, if we learn to work within their limitations.