Greg Egan is truly one of the most creative minds on the planet. He has a book called Dichronaughts that's set in a universe with 2 space and 2 time-like dimens

Greg Egan is truly one of the most creative minds on the planet. He has a book called Dichronaughts that's set in a universe with 2 space and 2 time-like dimensions. It's very hard to get your head around but the result is a universe with a hyperbolic geometry where movement on one axis implies changing your shape entirely.