  Kashiwara and Saito have a geometric construction of the infinity crystal for
any symmetric Kac-Moody algebra. The underlying set consists of the irreducible
components of Lusztig's quiver varieties, which are varieties of nilpotent
representations of a pre-projective algebra. We generalize this to
symmetrizable Kac-Moody algebras by replacing Lusztig's preprojective algebra
with a more general one due to Dlab and Ringel. In non-symmetric types we are
forced to work over non-algebraically-closed fields.
