  In all existing quantum walk models, the assumption about a pre-existing
fixed background causal structure is always made and has been taken for
granted. Nevertheless, in this work we will get rid of this tacit assumption
especially by introducing indefinite causal order ways of coin tossing and
investigate this modern scenario. We find that an ideal-shape and
fast-spreading uniform distribution can be prepared with our new model. First
we will show how an always-symmetrical instantaneous distribution appears in an
indefinite causal order quantum walk, which then paves the way for deriving
conditions that enables one to interpret an evolved state as a superposition of
its definite causal order counterparts which is however in general prohibited.
This property of temporal superposition of states can be generalized from
two-process scenarios to cases where arbitrary many $\mathcal{N}$ processes are
involved. Finally, we demonstrate how a genuine uniform distribution emerges
from an indefinite causal order quantum walk. Remarkably, besides the ideal
shape of the distribution, our protocol has another powerful advantage, that is
the speed of spatial spreading reaches exactly the theoretical limit in
contrast to conventional cases where one may encounter the well-known issue of
a $1/\sqrt{2}$ degeneration.
