"Horde Masters" Design Document

### Is your feature request related to a problem? Please describe.

I find idle survival (finding a building and staying in it) in CDDA to be far too easy, mostly for the following reason: provided you've chosen a remote location to settle, no monsters will ever find you unless you go out of your way to provoke them. This is the post-apocalypse; even housed in a secluded forest, you should never feel truly safe.

### Solution you would like.

#63194, but a little more aggressive.

A new mid-to-late game periodic event where a zombie horde will spawn and hunt you down endlessly until you kill its "Horde Master", an intelligent but heavily corrupted feral (perhaps with unique abilities, equipment, spells, a name, etc.) that will track the player's position and direct the horde to follow you until it is dead. Killing the Horde Master will cease the horde's long-term pursuit, but not their immediate hostility.

Horde Masters will be displayed on the map when first sighted, pausing the game. Their hordes are faster than walking speed, so escaping them on foot is not an option. Horde Masters will never spawn while a portal storm is on the map, but portal storms may spawn while Horde Masters are on the map.

Horde Masters start appearing around the first month of Summer (if the starting date is after Summer, then one month after the game starts), and then roughly once a month. Frequency and starting date should be a user option. Each successive horde is stronger than the last, with the first being roughly 8-10 zombies and then later hordes being significantly larger and/or more evolved.

Horde Masters could easily be turned on/off as an option if needed.

With Horde Masters, base defense becomes necessary. The player will always be kept on their toes, and may very well be caught off-guard by the first Master -- in-universe, there could be hints to hordes attacking, but nothing confirmed until it starts happening.

### Describe alternatives you have considered.

Feel free to suggest alternatives, this is a draft.

Anticipated Issues:

- "The player can just drive away from the horde!"

Yes, they can. This requires fuel, and driving back and forth between safe areas creates tedium that will eventually become more boring for the player than fighting the horde.

### Additional context

Lore justification (SPOILERS):
The Blob is "is digesting our universe", and is "very intelligent, but it is an intelligent being that is in another room playing video games", and "every living thing on earth is infected by the blob". Using these facts, we can extrapolate that Horde Masters are pursuing the player for the Blob's purposes, intelligently using the extradimensional Blob inside everything as a tracker, not *because* the Blob is explicitly ordering it to, but because that is what it is designed to do.

Start by reviewing issue #63194 and the proposed Horde Masters behavior in this issue, including timing, escalation, tracking, portal-storm interaction, and configuration. No implementation files, tests, or entry points are named; done would require turning this draft into an agreed, implemented feature with the described horde and Horde Master behavior.

Written by the indexing model from the issue text.