Atomistic simulations have been used to study thin film growth through the impact of energetic acetylene molecular clusters with three nonrigid, diamond (111) surfaces in vacuum. The surfaces considered include clean, bare-carbon diamond (111), clean hydrogen-terminated diamond (111), and hydrogen-terminated diamond (111) partially covered by a hydrocarbon film. The velocities considered are in the hyperthermal region (corresponding to external kinetic energies of about 20 eV/molecule) and are comparable to those that can trigger shock-induced chemistry in energetic materials. The collision caused the molecules in the cluster to undergo addition chemistry with other cluster molecules and/or with the surface resulting in thin film growth. We discuss the effect of surface reactivity on the products of the collision, including the resulting thin film morphology.