  In this paper, we study two-term tilting complexes for preprojective algebras
of non-Dynkin type. We show that there exist two families of two-term tilting
complexes, which are respectively parameterized by the elements of the
corresponding Coxeter group. Moreover, we provide the complete classification
in the case of affine type by showing that any two-term silting complex belongs
one of them. For this purpose, we also discuss the Krull-Schmidt property for
the homotopy category of finitely generated projective modules over a complete
ring.
