For a while, in custom world types, I've been wondering: Why not allow for more than 1 biome, rather than all biomes or 1? In the buffet world type, it's almost the same - you can only select 1 biome. What I'm thinking is that you can select multiple biomes to be used in the world generation. An example would just be clicking once to add a biome, and clicking again to remove it. This would make the world generation more immersive, whether it be the custom world type coming back, or the buffet world type being improved. This would make it easier to make more specialized survival challenges - such as only the cold biomes, only the warm biomes, or only the temperate biomes. Also, it would be interesting to be able to affect the world gen based on the x and z coordinates - such as warm biomes at x = 0, cold biomes at x = 20,000, or mountain ranges based on the z axis. This would make it possible to make far more customized worlds without the use of world painter or MCedit possible.