It was thought that 11 dimensional string theory and twisted space theory could not both be true but Witten says string theory does fit nicely into twisted space of 6 dimensions composed of 3 sets of complex space each of which has a real and an imaginary (sq root of -1) dimension.

Hum, E8xE8` or SO(32) are needed for anomaly cancellation, imho. Is it possible that it just a case that twisted space describes a `subset` of string theory, er, namely the 6 compactified spaces....(shot in the dark) Sounds interesting, Have you a link?

Don, I think that you are talking about twistor space theory. Witten is known for his efforts to try to unify strings with twistors