The Interscale Galactic NucleI Simulations (IGNIS) project consists on a large suite of ultra-high resolution cosmological hydrodynamic simulations that for the first time explicitly resolve the inflow of gas from cosmological accretion down to the inner 0.1 pc surrounding the central massive black hole and the multi-scale impact of active galactic nuclei (AGN) feedback.  IGNIS leverages recent major advances in galaxy formation simulations and the physics of black hole fueling and feedback, implementing:

1. Multi-phase interstellar medium (ISM) physics from the FIRE project.
2. A novel hyper-Lagrangian refinement technique that increases the resolution dynamically closer to the black hole.
3. Explicit treatments of black hole growth and feedback on scales comparable to the accretion disk.

By applying this technique to a broad range of redshifts, galaxy types, and cosmological environments, IGNIS aims to:

1. Identify the primary mechanisms responsible for gas transport across scales and ultimately fueling AGN.
2. Understand the impact of accretion-disk winds and radiative AGN feedback in multi-phase gas from galactic nuclei to circumgalactic medium scales.
3. Incorporate the results obtained for a broad range of conditions into physically motivated sub-grid accretion and feedback prescriptions for large volume simulations.
4. Provide a solid basis to interpret a plethora of galaxy and massive black hole observables across redshifts.