Hey everyone, I have recently been working on a large scale survival map, with floating islands. Each island is a different biome, and includes something special. For example the island I am currently working on is a plains biome, with a blown-up village. What I would like to do is have a few creeper spawners under the ground, but all of the spawners I have created using command blocks never seem to work, or they only spawn once, then never again. I have tried changing difficulty, and settings in the command. I also have no mods to conflict with mob-spawning.
I was hoping that someone here might know how to create a mob-spawner out of just a command block. One that can detect players in a certain vicinity, then begin to spawn mobs at a set rate. I have seen it done before in videos, such as Bodil40's parkour adventure maps. I really want this survival map to be great, and any help with this would be greatly appreciated!