  First- and second-order temperature driven transitions are studied, in a
lattice gas driven by an oscillatory field. The short time dynamics study
provides upper and lower bounds for the first-order transition points obtained
using standard simulations. The difference between upper and lower bounds is a
measure for the strength of the first-order transition and becomes negligible
small for densities close to one half. In addition, we give strong evidence on
the existence of multicritical points and a critical temperature gap, the
latter induced by the anisotropy introduced by the driving field.
