IMO the creeper should only cover the surfaces of bricks that are apart of the build itself, not amass upon itself, if you know what I mean.
In other words, it should only place another creeper brick next to itself if at least one side of the new creeper brick is going to touch a permanent brick. Basically covering the build itself, not placing creeper bricks where it's unnecessary.
This map is a Creepageddon map. There is no CreepKill. The goal is:
a) be the last person alive
b) be alive when the timer runs out
I hope you realize that a) is going to make people want to block other people all the time.