Steady and unsteady separation on a flat-plate generated by a localized three-dimensional pressure gradient has been studied with Direct Numerical Simulations for a range of flow parameters. The fundamental characteristics of this type of flow have been analyzed and three distinctly different topologies were found. Fundamental features described for three-dimensional separated flows in general as well as for the flow over a hemisphere-cylinder in particular could be reproduced. The closed separation topologies are all very similar near the line of separation. One pattern in particular displays features that closely resemble the flow over a cylinder with a hemispheric cap. In addition to the closed separation patterns, we also found an open separation topology that may not have been documented before.