Computing the universe has been a very successful activity over the past decades. We have now entered the era of precision cosmology, and N body simulations have to face new challenges to be able to contribute to the discovery of new physics in the universe. On smaller scales, baryons play an important role, and our understanding of galaxy formation still remains very vague. Feedback processes play an fundamental role in setting up galaxy properties and how they impact their environment. Recently, galaxy formation simulations have gained complexity and realism, introducing new simulated processes like magnetic fields and radiation fields. Our hope is to shed light on fundamental processes in galaxy formation, and to estimate how they will feedback on the mater distribution on large scale, leading to a more accurate, unbiased measurements of dark matter and dark energy properties.