World type or Game mode.

So my idea is that you have a mod type or extra option that allows you to make a new world type or gamemode (e.g Creative) or world type (e.g Superflat). In this new world type you can choose, what biomes, ores, mobs, mods (from your list) and more spawn and work in this gamemode. Another idea could be that (like the plugins for windows 10 edition) you can change how things behave with other objects or mobs e.g you could make a zombie die if it touches ice or you could make dirt turn into water if it touches ice. I know that this would be very hard to put into Mcreator and would be amazing if we could just do the last thing (change how Minecraft's mobs act) but I would love to see this added.