Fundamental insight into the polymerization behavior and structural evolution of highly cross-linked polymers synthesized from the chain polymerization of multifunctional monomers will benefit a number of current and emerging applications. This contribution reintroduces' an off-lattice kinetic gelation model with refinements to the representations of monomer mobility, structure, and functionality, which more realistically capture low conversion propagation events during cross-linked network evolution. Intramolecularly cross-linked macromolecules (ICMs) are formed by simulation of a single propagating radical within a volume containing ca. 100 000 monomer units. Effects of monomer mobility, structure, and functionality on the relative size, kinetic chain length, and intramolecular cross-link density of ICMs are reported. Finally, aspects of percolation theory are applied to this off-lattice kinetic gelation simulation. The fractal dimension corresponds to the theoretical value for a lattice animal created by a three-dimensional percolation model and it is independent of conversion. Overall, this contribution demonstrates the utility of a unique approach for kinetic gelation simulation of multifunctional monomer polymerizations that affords more realistic representation of monomer structure and dynamics than traditional, lattice-based models.