This paper presents a detailed simulation study of a rich cluster of galaxies in a flat, low-density universe. The authors simulate the assembly of a massive cluster and the formation of its constituent galaxies, focusing on the collapse, star formation history, and orbital motion of galaxies more luminous than the Fornax dwarf spheroidal. They track dark halo structure consistently for galaxies more luminous than the SMC. The simulations, which resolve about 200,000 dark matter particles and 5,000 distinct galaxies within the virial radius, are used to check numerical convergence and to reproduce observed properties of isolated spirals outside clusters. The semi-analytic modeling is tuned to match observed luminosity functions, mass-to-light ratios, luminosity, number, and velocity dispersion profiles, and morphology-radius relations in real clusters. The explicit treatment of galaxy merging demonstrates that it quantitatively accounts for the observed population of bulges and elliptical galaxies in clusters. The study also investigates the formation history of the cluster and its galaxies, including star formation, merger rates, and the evolution of stellar populations. The results highlight the importance of subhalo identification and the impact of substructure on cluster properties.This paper presents a detailed simulation study of a rich cluster of galaxies in a flat, low-density universe. The authors simulate the assembly of a massive cluster and the formation of its constituent galaxies, focusing on the collapse, star formation history, and orbital motion of galaxies more luminous than the Fornax dwarf spheroidal. They track dark halo structure consistently for galaxies more luminous than the SMC. The simulations, which resolve about 200,000 dark matter particles and 5,000 distinct galaxies within the virial radius, are used to check numerical convergence and to reproduce observed properties of isolated spirals outside clusters. The semi-analytic modeling is tuned to match observed luminosity functions, mass-to-light ratios, luminosity, number, and velocity dispersion profiles, and morphology-radius relations in real clusters. The explicit treatment of galaxy merging demonstrates that it quantitatively accounts for the observed population of bulges and elliptical galaxies in clusters. The study also investigates the formation history of the cluster and its galaxies, including star formation, merger rates, and the evolution of stellar populations. The results highlight the importance of subhalo identification and the impact of substructure on cluster properties.