creeper that grows

[C10B]

At the moment, creeper comes from a single source.
But what would happen if creeper just existed on the map already, and it could grow on its own if left untouched? So a small blob of creeper left anywhere on the map could grow over time. Capping a source at the moment can make a level easyish. Having to mop up the whole level entirely would be great, with no particular source to aim at. I guess this would be easy to code too.
Any thoughts?

[Sqaz]

I think if you do that the game will be less strategic, now you can do paratrooper attacks on weak emitters, or block a choke point so you stop the progress of the Creeper for example.

Also it would be impossible to let Creeper grow on higher elevations as without emitters Creeper will always flow to the lowest level and grow there.

And if Creeper would just grow, how fast will it grow and at which rate, I think if you'd have to think of those things it will make map making incredibly hard cause the Creeper is everywhere the same, while now you can just place some extra emitters or put their intensity higher.

[C10B]

I don't think I would rule out emitters as you are right, all creeper would fill the valleys otherwise and leave the high ground dry.