Spatial distribution of dark matter halos in the new S¹ × ℝ² StePS simulation at different redshifts, in comoving coordinates. Due to the zoom-in geometry, and the fact that low-mass halos form first, halos first appear close to the central axis, where the resolution is highest, and the smallest halos can be resolved. As structure formation proceeds towards higher masses, halos can later be found at larger radii, where the resolution is lower, and only more massive halos can be resolved. Towards larger $\varrho =\sqrt{x^2+y^2}$ only increasingly massive halos are resolved, so the apparent decline in number density at large 𝜚 is a selection effect.