Halo's aim assist system is comprised of two parts: Auto-Aim and Magnetism. Auto-Aim shifts the projectile trajectories towards a target. This is indicated by a red reticle. In Halo 1, the Auto-Aim system was very simple, as projectiles to traject toward the nearest part of an enemy. In Halo 2 onwards, the Auto-Aim system was enhanced to prioritize headshots. This made Face painting in Halo 2 onwards much easier. If a projectile's hitscan range is less than the auto-aim range, shot leading will be required, ALA Halo 3's Battle Rifle and Halo 1's Pistol, and many other weapons in the sandbox of these two titles.