Numerical simulations have become an indispensable tool for understanding galaxy formation. Over the past decade, increasingly sophisticated physical models have enabled simulations to reproduce many of the observed properties of galaxies across cosmic time. Yet reproducing galaxies is not the same as understanding the underlying physics. The life cycle of baryons, from the collapse of giant molecular clouds and the formation of stars, to stellar feedback, the circulation of gas through the interstellar and circumgalactic media, and ultimately the escape of ionizing radiation, is governed by tightly coupled processes spanning many orders of magnitude in scale. These processes shape both galaxy evolution and the reionization of the Universe, yet many of them remain poorly understood. In this talk, I will discuss our efforts to model these interconnected baryonic processes within numerical simulations, with particular emphasis on star formation, stellar feedback, cosmic rays, and radiative transfer. I will highlight what we have learned from these models, where the current limitations lie, and how simulations can be more directly connected to observations. Finally, I will offer some thoughts on future directions for galaxy formation simulations and on opportunities for stronger collaboration between theoretical and observational studies, particularly within the Korean astronomy community.