Migrating Creatures

What it does: creatures leave home. Wolves come down from the mountains into the Black Forest, boar herds drift out of the Meadows, a band of greydwarfs wanders into the fields, lox roam across the Plains, and later in the game a fuling war party passes through the forest. They travel the world on foot, day and night, whether anyone is near them or not, so what you meet depends on where it is now, not only on where you are. Nothing announces it: no message, no marker. You find out when a lone wolf is standing at the edge of your meadow.

The biome is no longer the whole story.

Version 0.2.0. Travelling groups, routes, herds, the safety rules and travelling enemy bands are in, tested in single player. Not yet tried in multiplayer or on a dedicated server.

Features

• Most travellers are alone. A group is a lone animal most of the time, sometimes a pack of two to five, and only rarely a herd. A herd is something you remember seeing, not a weekly event.
• They go somewhere. Each group gets a route across the land from one biome to another, winding round deep water, cliffs and your bases. Some legs it walks with purpose, near-straight and steady; on others it ranges, wandering around its line and stopping at the water's edge or on open ground. Now and then a group settles somewhere for a day or two before moving on, and when it reaches the end of its route it stays there until it moves on for good.
• The world keeps moving when you are away. Far from players a group is only a position on the map, so a dozen of them cost almost nothing. When you come within 120 m it becomes real creatures; when everyone is 180 m away it goes back to being a position and carries on.
• A fight is for keeps. A creature from the migration table that turns on you (or on anything else) leaves its group for good and stays where it is: it never vanishes because you backed off, and it keeps its wounds like any creature.
• Enemies travel too, in bands. Fuling war parties, trolls, greydwarfs and their brutes, draugr and fenrings set out from their own biome into the ones next door. A band fights like the creatures in it, players and other creatures alike, its members come to each other's help, and when the fight is over the survivors travel on together. Night bands only travel after dark.
• Rare until you are ready. Every band, and every hostile creature in the table, belongs to a tier of the game. For each boss you have not beaten yet it gets much rarer: in a fresh world the travellers are boars and greydwarfs, trolls are a rare sight, and a fuling war party is almost unheard of until Moder is dead.
• Nothing is reset. While a group is out of sight its members keep their health and stars, so a group that took damage some other way is still hurt when it comes back into view.
• Kept fair:
  • routes never pass within 60 m of a player ward, so a migration does not walk through your base while you are away;
  • migrants never target or damage buildings;
  • at most one star by default;
  • at most 12 groups in the world and 8 creatures in a group;
  • by default, wolf and lox routes keep out of the Meadows.
• Vanilla leaves them alone. Migrants do not despawn at dawn, do not count toward a biome's own spawn limits (the forest still spawns its own creatures), and are not pulled back to a spawn point.

The migration table

BepInEx/config/marc.valheim.migratingcreatures.table.txt, written on first run. One migration per line:

CreaturePrefab | SourceBiome | DestBiomes | MinCount | MaxCount | Speed | Frequency | SeasonWindow | AvoidBiomes

Add any creature you like. mc_reload in the console re-reads it.

An optional 10th column, Tier, sets a row's progression tier (0 Meadows ... 4 Plains ... 7 Deep North). Left empty, a hostile creature gets its source biome's tier and an animal 0. Write 0 to make a row ignore progression.

Bands

BepInEx/config/marc.valheim.migratingcreatures.bands.txt, written on first run with notes on every setting. One block per band:

[FulingWarband]
Members = Goblin 2-5; GoblinBrute 1 30% needs 3; GoblinShaman 1 20% needs 2
Home = Plains
Enters = Plains, BlackForest, Mountain, Meadows
Heads = BlackForest, Mountain, Meadows
Time = Any
Weight = 1
Speed = 1.5

• Members: each creature with a count (2, a range 2-5, or a list to pick from, 1,1,2,3 = alone half the time), an optional chance (30%) and an optional needs N (only when the band already has N members). The first line leads.
• Home (where it starts), Enters (the only biomes its route may touch), Heads (where it is going), Avoid.
• Time: Any, Day or Night. A band only sets out in its time, and outside it holds where it is.
• Weight (against the table's Frequency), Tier (default: the Home biome's), RequiresKeys (global keys that must all be set, e.g. defeated_bonemass), Speed, RouteLength, Lifetime.
• StayTogether (default yes: a member that fights stays with the band), Assist (default yes: pack-mates within AssistRange, 30 m, join a member's fight).

mc_bands in the console lists every band and table row with its chance of being the next group right now.

Config

BepInEx/config/marc.valheim.migratingcreatures.cfg, also in Configuration Manager (F1): group budget, how often groups start, group size weights, lifetimes, the materialise and dematerialise distances, travel modes, route rules, ward distance and the star cap. Section "7 - Bands and progression": BandsEnabled, MaxBands (3 at once), BandWeightScale, EarlyTierFactor (0.15: each boss short multiplies a weight by this), ProgressionKeys (the boss keys, in tier order) and ProgressionOverride (testing).

Console (F5)

Multiplayer

Install on every client and on the server. The server runs the travelling groups; each client runs the herds it is near.

Coming later

Signs of a passing herd (tracks in mud and snow, distant sounds, wildlife fleeing ahead of it), travelling groups leaving kills behind for The Dead Remain's scavengers, seasons, and routes along coasts and across shallows.

Install

Install with r2modman / Thunderstore Mod Manager, or drop MigratingCreatures.dll into BepInEx/plugins/MigratingCreatures/. For multiplayer, put it on the server too.