The simulation code GIZMO is a flexible, multi-method magneto-radiation-hydrodynamics+gravity code. The code lets you solve the hydrodynamic equations using a variety of different methods -- whatever is best for the problem at hand. In particular, it introduces a couple of new, Lagrangian Godunov-type methods, that allow you to solve the fluid equations with a moving particle distribution that is automatically adaptive in resolution and avoids the advection errors, angular momentum conservation errors, and excessive diffusion problems that seriously limit the applicability of “adaptive mesh” (AMR) codes, while simultaneously avoiding the low-order errors inherent to simpler methods like smoothed-particle hydrodynamics (SPH). But, if you want to use SPH -- either in “traditional” form or “modern” (more accurate) forms, or use a mesh, you can do that too with GIZMO!