Abstract: The large scale distribution of gas in the Universe contains
the answers to many mysteries, such as the nature of dark matter, the sources of ionizing photons, and global trends in star formation. Cosmological simulations are the only way to understand these questions. I will talk about our ongoing simulation effort, ASTERIX. A particular focus of ASTERIX is z > 2, the era probed by upcoming NASA flagship missions JWST and WFIRST. In pursuit of this focus, we have implemented novel models for hydrogen and helium reionization, and run a 250 Mpc/hbox simulation with a resolution comparable to Illustris-TNG 100. I will discuss our models and present some preliminary results at z > 5.