HaloMods "Classic" Read-only Archive

ive been looking around the forums looing for a way to create new halo maps and from what ive seen its not posible, i was just wondering if some one could tell me in detail why its not posible atm.

Im just wondering, from what ive seen around the file forums it seems like its not posible to add new vichels,weapons,new maps nothing like HaloCE now am i mistaken or not