Breeding & Stud

Breeding is the only source of new horses after genesis, and it is designed so that what was sold as rare stays rare. Every rule below is enforced by the platform, not by policy.

How a mating works

You breed a stud with a mare. Use two of your own horses, or pay another owner's advertised fee to use theirs — see Standing at stud below. The foal is a brand-new NFT that inherits from both parents:

• Bloodline — a foal's bloodline is rolled from both parents. The better the stud, the better your odds; the weaker parent holds them down (see the odds table below). You can't launder a cheap horse into a great one — a Cosmo mare bred to a Hyperion is most likely a Neutron, with a real but not guaranteed shot at Starfire. And the elite is a wall: the only way to a new Hyperion is to pair two Hyperions — and two Hyperions throw a Hyperion 90% of the time. The wall is not the odds, it is the door: there are 102 Hyperions in existence and you need two of them. And there is one door inside that door — a cover by the King or the Queen on another Hyperion, the only pairing in the game that can produce a third pure blood. See The Hyperion tier.
• Coat — each coat gene (base colour, pattern, hair) is inherited separately: a coin flip between the parents, with a ~2% mutation chance that re-rolls from the public mint odds. Super Rare colours can never arrive by mutation, only by inheritance — their population can only hold or shrink. See Coat Colours.
• Ability — racing genetics combine from both parents with natural variation. Two fast parents tend to throw fast foals; nothing is guaranteed. Ability is hidden at birth and revealed by racing.
• Sex — rolled at birth. A horse is either in the racing pool or the breeding pool at any time, never both.

Foal bloodline odds

The stud you choose sets your chances. A better stud lifts the odds; the weaker parent anchors them.

Sire × Dam	→ Cosmo	→ Neutron	→ Starfire	→ Hyperion
Cosmo × Cosmo	100%	—	—	—
Cosmo × Neutron	55%	40%	5%	—
Cosmo × Starfire	35%	45%	20%	—
Cosmo × Hyperion	22%	53%	25%	—
Neutron × Neutron	30%	60%	10%	—
Neutron × Starfire	15%	50%	35%	—
Neutron × Hyperion	8%	42%	50%	—
Starfire × Starfire	10%	30%	60%	—
Starfire × Hyperion	—	15%	85%	—
Hyperion × Hyperion	—	5%	5%	90%

Pay for a Hyperion cover and a Cosmo mare gets a genuine 25% shot at a Starfire — that's what the fee buys. But two Hyperions are the only pairing that can ever produce a new Hyperion. That pairing throws one 90% of the time — the scarcity comes from owning two Hyperions at all, not from the roll. The roll happens when the cover is booked, against this fixed table, and the table is published before anyone pays. What we do not claim is more than that: the draw is made by ROX, so you are trusting us on how it was made — Fairness & RNG says so plainly rather than letting you assume otherwise.

One pairing is not on this table, because it is not a roll. When the King or the Queen covers another Hyperion, the bloodline roll is skipped and the foal is a Hyperion, certainly — not 90%. Every other row above holds exactly as printed, including for the King and Queen themselves: a royal cover on a Starfire, a Neutron or a Cosmo obeys this table like anyone else's, and this table gives those pairings a 0% chance of a Hyperion. The royal privilege reaches inside the Hyperion ladder and nowhere else. See The Hyperion tier.

These odds are the contract's. bloodline_odds() in the database and oddsCum in BreedingMinter carry the same matrix, and this table is generated from it — if they ever disagree, the contract is right and this page is wrong.

Three bloodline ladders — ROX, ZED and the mix

ROX horses and migrated ZED horses race together, but they are different species and their bloodlines are not one scale. A ZED horse keeps Nakamoto or Szabo; a ROX horse has Hyperion or Cosmo. Nothing is translated between them.

That gives three ladders, and a pairing always draws from exactly one:

the pairing	the foal's ladder	weakest → strongest
ROX × ROX	ROX	Cosmo · Neutron · Starfire · Hyperion
ZED × ZED	ZED	Buterin · Finney · Szabo · Nakamoto
ROX × ZED	Hybrid	Supernova · Blazar · Magnetar · Zenith

A cross can never produce a Hyperion, and never a Nakamoto. Mixed blood is its own thing — a new generation, with its own four names. This is not a balance tweak; it is the rule that stops migration inflating either crown.

The odds are the same matrix for all three. Each parent is ranked one to four within its own ladder, and the table above is reused, so a ZED pairing gets the ZED shape and a cross gets the hybrid shape. No separate numbers, nothing invented.

That means Zenith sits behind exactly the same wall as Hyperion: the only pairing that can produce one is Hyperion × Nakamoto — the crown of both ladders at once, which is rarer than owning two Hyperions.

a few worked examples	→	result
Buterin × Buterin		100% Buterin — matched pairs never breed up
Szabo × Nakamoto		85% Szabo, 15% Finney — no Nakamoto
Nakamoto × Nakamoto		90% Nakamoto — ZED's crown, same wall as Hyperion
Cosmo × Buterin		100% Supernova
Hyperion × Szabo		85% Magnetar, 15% Blazar — never a Hyperion
Hyperion × Nakamoto		90% Zenith

ROX × ZED covers book like any other. The same stud, mare and fee rules apply, and the foal's bloodline is rolled from the table above.

The Hyperion tier — the crown, and the one door into it

Hyperion has four rungs, and they are not equal:

Rung		At genesis	Mint price
DN0	The King and the Queen	2	$3,000,000 · $5,000,000
DN1		20	$100,000
DN2		30	$50,000
DN3	The entry rank	50	$25,000

Two Hyperions who are not the King or the Queen can breed a Hyperion at any rung from DN1 down — a good pairing is not stuck at the bottom. What they can never produce is a DN0. That is not a policy we promise to keep; it is a floor written into the breeding function, and 40,000 simulated covers of a DN1 on a DN3 returned not a single one.

A royal cover

The King and the Queen are the only two horses in the game that can make a third. Covering one of them onto another Hyperion changes two things at once.

The bloodline stops being a gamble. An ordinary Hyperion pairing throws a Hyperion 90% of the time, so one cover in ten comes back as something else entirely — a $5,000,000 Queen could produce a Neutron. A royal cover on another Hyperion is a Hyperion, certainly.

And purity dilutes one rung at a time. A pure blood does not pass down a rung; it passes down purity, and purity thins by one step for every rung its partner stands below the crown. The chance of a new pure blood is 5% for each rung, and whatever is left lands on the rungs from DN1 down to the partner's own — never below the partner, and weighted so the best rung is always the likeliest:

The mare or stud covered	→ DN0	→ DN1	→ DN2	→ DN3
DN0 (the other royal)	20%	80%	—	—
DN1	15%	85%	—	—
DN2	10%	60%	30%	—
DN3 (the entry rank)	5%	47.5%	31.7%	15.8%

Read the bottom row as an owner. You have the cheapest Hyperion in the game, the $25,000 entry rank. You pay for a royal cover, and you have a 47.5% chance of a $100,000 horse, a five percent chance of something that has no price — and, whatever happens, you cannot come out below the mare you started with. That is the most valuable service on the platform, and it is why the King stands at stud at all.

What you cannot buy is a certainty. Nineteen royal covers in twenty do not produce a pure blood. The 5% is genuinely 5% — the same published table as every other pairing, and no amount of paying changes it. See Fairness & RNG for exactly how much of a roll you can check. Take a royal cover for the odds on the whole row, not for the crown.

And the door is narrow by construction. A horse's breeding slots are 5 − generation, computed by the database rather than stored, so they cannot be topped up, bought, or granted. The King has five covers and the Queen has five. That is ten royal covers in the life of the game, so there can never be more than twelve pure bloods in existence — the two minted and at most ten bred, and in practice far fewer, because most of those ten will come back DN1.

Every bred Hyperion, at any rung including DN0, still takes one of the 100 crown numbers, each issued once. The elite remains capped at 202 ever. The royal ladder changes how good a bred Hyperion can be. It does not add one.

Migration does not open a side door. A ZED horse cannot be bred into a Hyperion at any rung, from any pairing, because a ROX × ZED foal is never a ROX bloodline at all — it is a hybrid. The crown is reachable only from inside the ROX ladder, exactly as it was before migration existed.

Generation decay — why the population cannot explode

Every horse carries a generation number: genesis is generation 0, their foals are generation 1, and so on. Breeding capacity decays as generations advance:

Rule	Value
Breeding slots	5 minus the horse's generation (so generation 5+ cannot breed)
Lifetime breeding actions	bounded by the slot rule above — a generation-0 horse has 5
Who is exempt	Nobody. The slot rule applies to every bloodline, including Hyperion, and to both sexes

Slots are not a stored number that could be edited, topped up or granted: the database computes 5 − generation on every read. A horse's fifth cover is its last whoever owns it and whatever it is worth.

Both sides spend a slot. A mare has five foals in her and a stallion has five covers in him, and a cover is refused the moment either runs out. That matters more than it sounds: if mares were unlimited, one mare covered by five different stallions would produce five foals and the stallion cap would cap nothing at all.

This bounds the total population at roughly 26× genesis — about 709,000 foals, ever, across every generation.

The mechanism is public and the bound is structural: 26,992 founders, an even split of 13,496 mares and 13,496 stallions, five breeding slots each, and slots decaying by one per generation until generation five cannot breed at all.

A cover needs one mare and one stallion, so it is capped by whichever side runs out first — and at an even split both sides hold exactly 67,480 slots in generation 0. That is why the number is robust: the cap does not depend on which stallions get used, only on how many slots exist, and no bloodline is exempt from spending one. A popular Hyperion sire changes who sires the foals, not how many can exist. The first generation of NFT racing games died of unlimited breeding; ROX cannot, by construction.

The economics

Breeding is how the middle of the market earns. A well-bred foal from proven parents sells on the marketplace for real money; a winning stud earns fees for years. Owners set their own stud fees — with one honest cap: a cover can never cost more than the horse itself would at auction. Nobody should pay more for the chance of a foal than for the whole horse.

Standing at stud

The stud market is where racing success turns into income. Any owner can stand a horse at stud, advertise it to every breeder on the platform, and set their own fee per cover.

How it works

1. Stand your horse. Move a stallion into the breeding pool and list it at stud with your asking fee. Its full public record — bloodline, genotype, rating, wins, coat and existing foals — is what breeders judge it by.
2. A breeder books a cover. They pay your fee, the mating runs, and the breeder keeps the foal. You keep your horse, your fee (less the platform's 5%), and one more entry in your stallion's progeny record.
3. The market sets the price. A G1 winner's book fills at a high fee; an unraced stallion has to price honestly. Fees are public, so the stud market prices genetics the way real bloodstock does — from the race record.

The one price rule

A stud fee can never be set higher than the horse itself costs. If the horse is listed for sale, the cap is its asking price — a cover can never cost more than simply buying the horse. If it is not for sale there is no asking price to measure against, so the cap is a fixed ceiling for its rank:

Rank	The bloodlines, on all three ladders	Cap when not for sale
4	Hyperion · Nakamoto · Zenith	$250,000
3	Starfire · Szabo · Magnetar	$5,000
2	Neutron · Finney · Blazar	$600
1	Cosmo · Buterin · Supernova	$120

The logic is simple: a cover sells the chance of one foal; a sale sells the whole horse. The cap keeps stud pricing honest and stops fantasy fees from cluttering the market. It is checked in the database every time a fee is set.

And a floor under it

A cover also has a minimum: half what ROX sells that rank for. Not half what the stallion sold for — half the published sale floor of its rank, so every stallion of a rank has the same minimum however its own auction went.

Rank	The bloodlines, on all three ladders	ROX sells from	A cover starts at
4	Hyperion · Nakamoto · Zenith	$25,000	$12,500
3	Starfire · Szabo · Magnetar	$2,500	$1,250
2	Neutron · Finney · Blazar	$250	$125
1	Cosmo · Buterin · Supernova	$25	$12.50

Why half, and not the whole price. A cover buys a chance at a horse of that rank, never a horse of that rank — even a royal cover on an entry-rank Hyperion is only a 5% shot at a pure blood, as the table above says. Charge the full sale price for a chance and breeding becomes strictly worse than buying, so nobody would ever pay for a cover. Half keeps breeding the cheaper road to a good horse, which is the entire point of breeding, while stopping anyone manufacturing rank-4 horses for pocket change.

The figures are read from the published sale floors when the cover is booked, not stored against each horse — so if ROX reprices a rank, the minimum cover for that rank moves with it and this table follows.

This is enforced in the database, not a guideline: a cover priced under the floor is refused when it is booked. Every stud standing when it landed was already above it, so no fee changed.

The house stud

The most famous entry in the stud book is the platform's own Obsidian Crown — the King, a DN0 Hyperion, one of the two pure bloods in existence, and on the marketplace at $3,000,000. He is listed at $87,500 a cover — comfortably clear of the $12,500 floor for his rank — and his stud listing is where that figure actually lives. One thing about that is not true yet, and we would rather say so: covers by ROX Official stallions, the King included, are not open. The stud book shows the fee, but a booking on a house stallion is refused today, so the only covers that can actually be taken are from stallions a player owns. He is rated into G2 like the Queen, although neither G1 nor G2 has been on the card since August, and he has five covers, ever — the same five every other genesis horse has. When house covers open, a cover by the King on a good mare will be the single biggest genetic upgrade money can buy — and every foal he sires will carry Hyperion blood into the open market.

Books and limits

Every stallion's covers are bounded by its breeding slots and generation, and Hyperions are not an exception — a genesis Hyperion has five covers in his life, exactly like a genesis Cosmo. Mares are bounded the same way: five foals, and the fifth is the last. Scarce covers are what keep a good stallion's fee strong, and here the scarcity is real rather than seasonal — when a great stallion's fifth cover is booked, there is no next season.