Throwing an active ragdoll and some refraction into the mix:
Just strap some boolean modifiers to an object, and meld it together with remesh (and optionally subsurf).
Performance goes down with scale obviously; but it’s stable so long as you don’t go crazy with it.
UPBGE 0.3 alpha, eh? Hmmmm… This would be so cool for some kind of horror game, or perhaps even a fantasy game. Having some kind of elemental or ghost with this kind of effect would be hella cool : D