We will discuss modular compactifications of M_{g,n} (the moduli space of smooth curves) and their birational geometry within the framework of the Hassett-Keel program. We classify the open substacks of canonically polarized curves with nodes, cusps, and tacnodes having a proper good moduli space. Using the S- and Theta-completeness criteria, we transform the problem into a combinatorial one where compactifications and flips can be described using cluster algebra theory. This approach yields a complete description of the Q-factorialization fan of \overline{M}_{g,n}(7/10) as a cluster fan.