We study theoretically propagation of a photon pair in a one-dimensional waveguide with an embedded array of closely-spaced two-level atoms. We predict, that atom-mediated interaction between the two photons enables an unexpectedly rich variety of two-quantum states. This strikingly simple setup features interaction-induced localization [arXiv: 1911.04113, PRL (2020, in press)], quantum Hall phase with Landau levels, interaction-driven topological edge states and Hofstadter-like butterfly as well as signatures of quantum chaos. Our findings enrich the understanding of many-body quantum matter and open new avenues to engineer entanglement by interactions.