OR Make a database. Kind of like Halo Reach where you can download maps and gametypes, pics, game modes, etc... They should add this to a section and include custom/ adventure maps, texture packs, you can create it then you can upload it on to the database. Its not cheating or anything cause you are not getting it from the pc and directly hacking. 4j can release like a DLC texture edit pack, where you can choose what color pixel and where to put it. As for mods, MAYBE they can release like some coding. I do have coding experience but its like Arduino.