>>716431004dude its basic bitch LOD shit.
very far distance gets 1 of 8 or so directional sprites based on coordinate system.
far distance sees multiple other sprites load in based on direction again to give a bit of parallax action
at medium range more stuff comes in and you get a 3D stylized model, potentially with 2D sprites making up other things like NPCs manning the walls.
at near range they become 3D as well.