The fast-ignition scheme in ICF has instigated research in a new area of laser-plasma interaction physics. This is due to the high laser-pulse intensities involved. At power densities of 1018 W cm-2, the physics becomes essentially kinetic in nature and highly nonlinear and hence requires special tools for its adequate description. Particle-in-cell (PIC) codes meet this challenge. Simulations obtained with the first three-dimensional PIC code VLPL (virtual laser plasma laboratory) developed at MPQ are presented for a broad variety of irradiation and plasma conditions. Particular attention is paid to a detailed comparison of numerical and experimental results and to the mechanism which accelerates the electrons to relativistic energies.