A demo planetary simulation of a giant impact, using the initial conditions created by the DemoImpactInitCond example with SEAGen and WoMa [1,2]. The scenario is a so-called canonical-like Moon-forming impact of a ~Mars-mass body onto the proto-Earth, at the mutual escape speed, with an impact angle of 45 degrees, set up as described in [3]. The initial conditions can be created via the DemoImpactInitCond example, see its README.md and the WoMa documentation for more details. Or the premade initial conditions can be downloaded directly with `get_init_cond.sh`. The default resolution is ~10^5 particles, set by the `N` variables at the start of the scripts. Note that here the simulation is cut short with an end time of just 15 h, for testing. Note also that this type of graze-and-merge collision is notoriously chaotic, so minor changes to the initial conditions can have large effects on the outcome, and a higher resolution than the default for this demo is required for convergence [3]. If you have just run the initial settling simulations, then please ensure you have configured and compiled SWIFT without the fixed-entropy setting before running an impact simulation. You may find it convenient to rename your SWIFT executables according to their configuration. [1] Kegerreis et al. 2019, MNRAS 487:4 [2] Ruiz-Bonilla et al. 2021, MNRAS 500:3 [3] Kegerreis et al. 2022, ApJL 937:2 L40 This example requires the code to be configured to use the planetary hydrodynamics scheme and planetary equations of state: --with-hydro=planetary --with-equation-of-state=planetary