Magical gene / no coat effect

Verdant

A horse that changes the ground it walks on: mycelium, moss or grass, creeping outward from wherever it stands. Three variants at one locus, every one of them needing two of itself — so a mycelium copy beside a moss copy is not half of each, it is nothing at all.

Crossing two of them

It paints nothing, and that is a gap

All five outcomes are wild types, so affectsCoat() is false, the locus is out of the texture key, and the gallery collapses it to one entry — four alleles for no catalogue growth at all, the same trick sex and the non-coat loci use.

The cost is real, and it is the same one milk has: a verdant horse is indistinguishable from an ordinary one until you watch the floor. It sits awkwardly beside healer, which draws a stripe precisely so a player can see what it does. A marking would be the fix, and it would want to be part of the locus rather than bolted on.

Its gene carrot

Gene key
horsegenetics.verdant
Priority
180 (magical band)
Alleles
mush moss grass n
Combinations
10, all carryable — 5 outcomes
Outcomes
wild, verdant-carrier, mycelium, moss, grass
Default allele
n
Wild frequency
mush 6%, moss 7%, grass 8% per allele
Founder draws
1 × nextFloat()
Coat effect
none, ever
Spread
at most one block per 60 ticks, within 2 blocks, 35% of the time
Built 2026-09-04, not yet play-tested

Nothing has watched a horse change a floor. The conversion lists in particular want a look: the risk is a horse eating something a player built with, and the lists are narrow specifically to avoid that. Checklist on To be verified.

The combination table

CombinationOutcomeEffect
n/nwildThe ground is left alone
any single variant copy, and any two different variantsverdant-carrierNothing — inert, and passes both on
mush/mushmyceliumMycelium spreads
moss/mossmossMoss spreads
grass/grassgrassBare dirt greens over

Three recessives at one locus

Every variant needs two of itself. That is a genuinely different shape from the rest of the mod, and it is worth sitting next to its nearest relative: milk’s two variants are also mutually recessive, but the pairing of them is lethal where this one is merely inert. Both are combination tables. Neither needs a word for what it is doing, and no dominance ranking could tell the two situations apart.

The consequence is that a verdant horse takes real work. With the commonest variant at 8%, about one wild horse in a hundred and fifty spreads grass, and the two carriers who could throw one look exactly like every other horse. Three variants at one locus also means a line bred toward one of them is drifting away from the other two — which is the sort of decision this model exists to create.

A cover, not a block id

The gene names one of three coversmycelium, moss, grass — and stops there. It does not name a block, because “spreading moss” is not one conversion: it is a small family of them, plus a rule about what it will and will not eat. That judgement needs the game’s block registry, so it lives in the translator, where the lists are deliberately narrow:

CoverEatsBecomes
myceliumgrass block, dirt, coarse dirt, podzol, rooted dirtmycelium
mossstone, cobblestone, andesite, gravel, dirt, coarse dirt, grass blockmoss block
grassdirt, coarse dirt, rooted dirtgrass block

Every entry is ground a player would expect to green over, and nothing on the lists is a block anyone builds with. Grass is the gentlest of the three and the only one that undoes damage rather than doing it.

One block a beat, on purpose

The translator converts at most one eligible block per beat, and picks a random candidate near the horse rather than the nearest one. Both are design rather than performance dodges: this is a horse changing the ground it walks over, and a player who leaves one standing in a field should come back to a patch rather than to a new biome. Picking randomly also makes the edge of a spread ragged instead of a perfect expanding disc.

It is skipped entirely in the horse dimension, for the same reason the light block is: nothing there should be able to rewrite the floor.