Racing

What it is. You drive a line through corners where speed and control genuinely trade off — flooring it understeers you wide, braking tucks you tight. The whole game is finding and holding the fast line lap after lap, usually against rivals.

Player fantasy. “I found the perfect line.” Mastery you can feel in your thumbs: the corner you used to blow now flows, and the clock proves it.

Pillars

The speed/line tradeoff is physical. Turn authority falls with speed (understeer), not grip that magically holds — so flat-out must NOT make every bend. Braking is the skill the genre sells; make it a dedicated control.
The clock never lies. Lap time is the honest, legible score. Every tenth is a decision you made three corners ago. Ghosts and rivals externalise it.
The track is the level. Corner radius, track width, and sequence author the difficulty. Design the geometry against the car’s turn radius, not by vibes.

The loop stack

Scale	The beat
Moment	Brake point → apex → throttle out; one corner, committed.
Encounter	A lap: chain corners into a rhythm, defend/overtake a rival.
Session	A race or time-trial; the grand prix; podium or PB.
Meta	Unlocked tracks/cars/tuning; championship standings; leaderboard chase.

Essential systems

System	Why it’s load-bearing
`system-enemy-ai`	The rival `driveLine()` is difficulty dial, completability proof, and skill-delta meter in one.
`system-difficulty-and-dda`	Rubber-banding, assist braking, racing-line guides — the ramp for a wide skill range.
`pattern-mastery-and-flow`	The corner you now flow through is the flow channel; the genre is a mastery curve.
`system-progression`	Track/car unlocks; tuning as a shallow build layer.
`pattern-risk-reward`	Late braking, cutting the kerb, the overtake into a blind corner.

Content & difficulty model

Derive geometry from the car, not the other way. The inequality chain: turn radius (speed ÷ steer-authority) < corner radius < track width. State it as a comment and assert it against the actual track and config (FUN.md law 3, §20).
Ordered checkpoints are the entire anti-cheat. Only the NEXT checkpoint counts; cutting the track advances nothing. This single rule replaces a collision-fence forest.
Off-track has a speed cap, not a wall — punish the sloppy line without a hard stop that reads as unfair.
The rival is your difficulty dial. One good driveLine() at scalable pace gives you completability proof (it finishes) and a skill-delta meter (a braking line beats a flooring line: 26.2s vs 27.7s in the campaign).
Track sequence is a tension curve. Alternate a technical corner-cluster with a flat-out straight so the player exhales; a circuit of nothing but hairpins reads as punishment, not mastery (see pattern-pacing-and-tension).
A ghost is the gentlest teacher. Racing your own PB (or the rival’s line) externalises the ideal line without a tutorial pop-up — onboarding by contrast.

Signature-mechanic seeds

Top-down racer but the track is drawn behind you and erased ahead — commit to a line you can’t preview (constraint; composes system-procgen-design).
Racing but braking recharges a boost you spend on straights — the tradeoff becomes an economy, not just a physics fact (mechanic-swap; system-economy).
Racing but every rival remembers how you overtook them and blocks it next lap (mechanic-swap + emergence; composes system-emergent-systems).
Racing but one screen, no scroll — the whole circuit visible, you optimise the global line (perspective/constraint).
Racing but cargo shifts your mass and turn radius as you deliver it — the car changes under you mid-race (mechanic-swap).

Common pitfalls

Grip instead of understeer. If more speed just means “more traction needed,” flat-out beats braking and the whole genre collapses. Authority must fall with speed; assert flat-out fails a real corner.
No dedicated brake. Braking-as-absence-of-throttle robs the player of the skill expression the genre is built on. Bind brake to its own key (corpus: WitchCup1276, DR1V3N WILD both do).
Rubber-band that erases skill. DDA that pulls rivals to your bumper regardless of your line makes lap time meaningless. Band the field, not the outcome.
Wall-collision anti-cheat. Fencing every shortcut is brittle; ordered checkpoints make cutting simply not count.
Wall-clock timing. Lap timing and physics must step on sim time, not Date.now, or the golden grand prix and PB ghosts drift (FUN.md law 6).

Anchors

anchor-trackmania — the definitive DNA for this genre’s soul: the clock as the only opponent, instant free restart as the practice loop, and a medal ladder that fits one track to every skill. Steal it when the fun is a solo line against the clock.
anchor-mario-kart — the competitive/arcade pole: the drift-boost skill ceiling on a trivial floor, and position-weighted catch-up that bands the field without erasing an earned lead. Steal it when rivals and spectacle matter more than the clock.

Still worth borrowing across both: anchor-tetris for the “one tuned verb, endless mastery” discipline, and anchor-into-the-breach for perfect-information honesty if you telegraph rival intent. Corpus references: WitchCup1276 (2023 gameplay #10), DR1V3N WILD (2024 gameplay #3).

Verify

Prove it against FUN.md §20 — Top-down racing: the driveLine() bot finishes laps; braking beats flooring (skill delta); cutting advances nothing; off-track speed cap holds; golden grand prix. See sandboxes/physics-lab for the vehicle-physics primitives and sandboxes/pathfinding-demo for the racing-line follower.

Composes with

system-enemy-ai — the rival driver is the beating heart of both difficulty and proof.
pattern-mastery-and-flow — cornering mastery is the flow channel; pace the track to keep the player in it.
system-difficulty-and-dda — assist braking and line guides widen the audience.