🔮 The Hidden Rules of Derby Owners Club — what the game never tells you

These are mechanics recovered by reverse-engineering the ROM — rules a player could never see, with what to actually do about each. Honesty tags: exact decoded byte-for-byte · strong decoded but approximate · inferred pattern-derived, not yet byte-proven.

Breeding — the game rewards matched bloodlines and taxes high averages

Foal stats are the parents' average — then docked exact

Internals = floor((sire+dam)/2), then a soft clamp: anything over 45 loses 5, under 10 gains 5, and internals are hard-capped at 45 (not 60/65). A 46 average comes out 41.
don't chase internals past ~45 from breeding — the ceiling is real, and pairing two maxed parents wastes the overflow.

The bloodline bonus — favorable & unfavorable pairs exact

For each of the six externals, the game scores how consistent the parents are: +1 if both are strong (≥12), +1 if both are weak (<4). High count → up to +3 stamina / +2 speed / +3 sharp.
breed like-to-like. Two parents strong in the same externals get rewarded; a mismatched pair earns nothing.

~6% of foals are random jackpots or duds exact

A hidden roll: ~3% of foals take −12 to a stat, ~3% get +12. Your "ruined" or "god-roll" foal was usually this, not your pairing.
re-breed; variance is built in. Don't over-read one foal.

Sex is a coin flip; aptitude is inherited bit-by-bit exact strong

Foal sex is a 50/50 random bit — you can't steer it. Dirt/turf aptitude is inherited per-bit from the parents' hidden masks, not averaged, so it can jump.
to fix aptitude, pick parents with the aptitude profile you want; averaging dirt numbers is the wrong model.

Racing — externals run the race; internals are the support cast

Externals dominate base ability strong card 0x5F–0x64

In controlled tests, swinging internals across their whole range barely moved base race ability, while externals drove it.
train and breed for externals first; internals are a smaller multiplier on top.

"Best distance" is about stamina, not speed exact

The distance table is a pace normalizer (distance × multiplier ≈ constant) — raw speed doesn't make a sprinter; sustaining the trip does.
match distance to stamina/aptitude. Use the Race Simulator's Best trip.

Stamina drain runs on a stat-total ladder exact

Per-segment drain is chosen by the sum of all six stats crossing thresholds (220/240/250/260/270/280/300) — higher totals drain less.
a high overall stat total improves stamina efficiency, not just the stamina stat.

Condition is stepped, not smooth exact

Condition acts through breakpoints at 92 / 95.5 / 96 / 99 / 99.5 — crossing one is a real jump.
push condition just past 96 (and 99) before a big race; 95 vs 96 is a step.

Whip grades: hold ×1, light ×2, hard ×3 — and it burns energy exact

The whip adds a graded speed boost but spends stamina.
save the hard whip for the closing stretch; early whipping empties the tank.

Bonding — the right words build it, the wrong words destroy it

Bond gain = multiplier × (100 − current bond), and it can go negative exact response names inferred card 0x3F

Each post-race response has a personality-specific multiplier (×2.0 great … −2.0 lowers the bond). A "Too soft" horse loves every response; a "Strict" horse rejects affection and only takes the firm option. Gains shrink as bond nears 100.
match the response to the personality — coddling a strict horse lowers its bond. Build bond early when it's low. (Use the Bond & Personality advisor.)

Feeding, roster & version

Each food has a known stat payload exact

Foods add specific Speed/Stamina/Sharp (and hidden extras); "growth" items behave differently from ordinary feed.
feed to the stat you want; don't waste rare growth items. (Use the Feeding Advisor.)

"Almighty" CPU horses have all six externals = 31 exact

A sentinel profile — strong at every phase.
spot them when scouting (Roster Browser flags them); don't assume a soft field.

The meta differs by version exact

Rev C = Rev D for CPU stats; DOC 2000 rebalanced a dozen horses; DOC '99 is a different roster/track/food set (no beer/banana).
know your version before importing "best horse" lists from another.
Full byte-level provenance & confidence per claim: see the knowledge base (HIDDEN_RULES.md, CARD_BYTE_MAP.md, ROM_ARCHITECTURE.md). These rules are decoded from the ROM — not folklore — and tagged so you know which is byte-exact vs still inferred.