So I built a creeper farm with the hoppers collecting the kill at y=62. The farm is in the air with a 33 block drop and 10 spawning platforms above that, putting the roof at y = 125.

So the well-understood mechanics of Minecraft put a spawning sphere around the player at 128 blocks (euclidean - meaning the Pythagorean theorem will work when calculating a distance between two points). Inside of 24 blocks, nothing spawns - so there is a chance to spawn a mob from 24 to 128 blocks from the player.

Despawning begins to occur at 32 blocks. A greater percentage chance the further away from the player the mob is until finally at 128 blocks despawning is 100%.

So given all that information, Y=190 is 128 blocks from Y=62 (the hopper/kill area). If I stand there or any higher, the creeper will despawn before it is killed. Alternatively if I stand close to the farm, I'm bringing the ground more and more into that spawning sphere of 128 blocks (and any holes/caves that may exists underground) so the chance of mob spawns outside of the farm increase, reducing efficiency.

So I put a AFK platform at Y = 187, which puts me just inside the 128 limit in order to minimize any ground spawning and virtually eliminate any UNDERground spawning.

But when I stand on this platform, the farm won't work. In THEORY it should, but it doesn't. All the tutorials also put AFK platforms just inside that 128 limit as well. What am I missing here?

Other notes:

- The PS field has mob spawning allowed
- I know server mob cap is a thing but I think given the theory above, it should at least work slightly better if I reduce the chance of outside-the-farm spawning in my loaded chunks.
- The farm works, I'm just trying to get it to work a bit better.