We develop a new approach, which we term Darcian Dynamics, to simulate two-phase (liquid-gas) flow in porous media, when the gas phase is disconnected in the form of ganglia. The method is based on the assumption of homogeneous fluid flow for the liquid, although it does allow for heterogeneous capillary thresholds due to the pore microstructure. Using techniques from potential theory, the hydrodynamic interaction between liquid and gas is expressed through an integral representation over the ganglia interfaces. We use a numerical method to solve the resulting integral equation, and explore conditions for the onset of ganglia mobilization as well as for subsequent events, such as break-up, coalescence and stranding. The interaction between the ganglia and the flowing phase is influenced by the capillary and gravity (Bond) numbers, and by geometric factors, such as size, orientation, and ganglia density. The latter effect depends on the hydrodynamic interaction in addition to the intuitively expected crowding effect.