Intensity, and the three beats
Once per second, per player, the Director scores your intensity: damage taken, hostile mobs within 24 blocks, darkness, being below 40% health, and camping in one spot. Quiet time decays it. Build-up erupts into a Peak when intensity crosses the threshold or the forced-peak clock runs out; the Peak ends when the horde is nearly dead or its timer expires; then Relax runs 120 to 300 seconds of fast decay. Dying puts you into a long Relax as mercy.
Tip: The default tuning aims for roughly one peak every one or two nights. Most nights are dread, not combat.
It owns the population
In the Overworld it cancels vanilla's random natural hostile spawning entirely and places every monster itself, on a phase-aware budget of around two near you in Relax, filling toward six plus two per threat tier during Build-Up, and none during a Peak because the horde is the population. Each placement is chosen with intent (a shadow past your torchlight, a seed on the road ahead, a cave pocket, occasionally a follower behind you) and runs the same fairness check the hordes use: never in your view cone with a clear line to your eyes, never in your own torchlight.
Tip: Set replaceNaturalSpawning to false for additive mode: vanilla spawning plus the Director. The farm-server setting.
The tier ladder
The arsenal is floored by your actual advancements and never drops once earned. Fresh spawn is grace: small hordes, no forced peaks, no specials, no sieges. Smelting an iron ingot unlocks forced peaks, Runners, Screamers and grudges; mining a diamond unlocks Brutes, sieges and the Miner; ancient debris unlocks veteran waves. On top of that, your current armour value scales wave size between 0.7x and 1.3x, and the zombies and skeletons it sends arrive in leather, then iron, then the occasional enchanted piece.
Tip: Stripping your armour shrinks the wave, it does not make the Director stupid.
Nothing happens in bright sun
Standing on the surface in daylight (skylight 12 or more, not thundering) means no peaks, no ambushers, no dread. But the day is borrowed: intensity keeps accruing (capped at 1.5x the peak threshold) and the forced-peak clock simply pauses, so everything you built up is waiting at dusk. A peak that legitimately starts at night is allowed to finish past dawn.
Dread between the waves
Most of the mod is the space between fights. During Relax at night: two or three Watchers stand motionless 20 to 30 blocks out for 20 to 40 seconds and then walk away; a single bang lands on one of your doors with nothing behind it; three to six stone-breaking sounds play inside a wall six to ten blocks away where nothing is digging. Camp behind walls through an unbroken peak and it leaves a waxed sign outside your door, placed the moment you look away, with a cave rumble to point you at it.
Mobs that play better
Creepers stalk like Weeping Angels. They look away and stroll casually while you watch them, close the distance when you do not, and drop the act inside six blocks so the vanilla hiss takes over. About 6% of zombies shriek on first sight of you and call a mini-horde, once per life. A zombie that locks onto you groans your position to every idle zombie within 16 blocks. Skeletons back off to reopen the range when you close, then keep shooting. Spiders lie dead still in the dark until you are within eight blocks. Zombies work wooden doors, if mobGriefing is on.
Tip: Every one of these has its own config toggle if a particular trick wears out its welcome.
The Miner
Camp underground long enough at tier 2 and a zombie with a pickaxe spawns 12 to 25 blocks away in a pocket with solid rock between you, and audibly digs toward you. It only breaks plain stone, never opens water or lava, never exposes an ore, never sets off a gravel cascade, and every block it takes is written to a ledger and grows back. The sound through the wall is the point.
Sieges, and the no-grief guarantee
Keep camping with a grudge-holding horde outside and a breacher walks up in an iron helmet, bangs on your wall as a warning, then chews a small crawl hole and comes in, baby zombie first. It only ever happens with mobGriefing on and only through blocks a player actually placed; natural terrain is immune. Every block any part of this mod breaks is ledgered and regrows a few minutes later, and the regrow loop runs even if you disable the mod mid-siege.
Tip: Killing the breacher cancels the breach.