Pickups & combat

Pickup boxes are scattered around each track. Drive through one to grab whatever's in it — there's a single slot per bike. Space (or A / X on a gamepad) fires it. Picking up a new type while holding one replaces the held pickup.

The four pickup types

Pickup	Color	Effect
Boost	yellow / orange	Speed multiplier. Throttle is multiplied by boostMul (default 1.6) for a few seconds.
Shield	blue	6 s bubble. Absorbs one mine or missile hit, then consumes itself. Doesn't block ramming.
Mine	red	Drops behind you with a 0.6 s arming delay. Proximity trigger spinouts the victim.
Homing missile	white	Acquires the nearest bike inside a forward cone (≤ 80 m, dot ≥ 0.3). Turn rate capped at 2.4 rad/s. 5 s self-destruct if it doesn't hit.

Implementation: src/game/components/pickup.ts + src/game/components/combat.ts.

The pool

Each pickup box draws from a weighted pool:

const POOL: PickupType[] = ['boost', 'boost', 'missile', 'mine', 'shield']

Boost is over-represented (2× weight) because it's the safe baseline — the offensive pickups are higher-stakes, so they should feel more like a treat than a default. Tune the ratio in pickup-spawn.ts if combat starts dominating racing.

Hit reaction

Whether it's a mine or a missile, the victim gets the same shared response:

• Linear-velocity damp × 0.55
• Yaw spinout of ±12 rad/s (random sign)
• Stun component for 1 s — stunOverrideSystem zeroes throttle / steer / brake / pitch on the victim until it expires
• Fire and Boost are not zeroed during stun — you can still pop a held pickup in self-defense

AI pickup usage

The four AI bikes fire their pickups via aiCombatSystem. Decision logic is in the pure helper shouldAIFire(held, throttle, |steer|, hasChaser, hasMissileTarget):

Pickup	Fires when
Boost	throttle > 0.85 (clean straight, never burns it scaled-down mid-corner)
Shield	held — sitting on it can't help
Mine	a non-self bike is within 12 m and behind us (dot < -0.4), OR mid-corner (`
Missile	throttle > 0.8 AND pickMissileTarget() finds a bike in our forward cone

Twelve unit tests cover the gates — see tests/unit/m9-ai-combat.test.ts.

Pickup respawn

When a player or AI grabs a box, it goes inactive for a few seconds before the next type is rolled. Spawn state is per-spawn-point (PickupSpawnState), not per-track, so respawn windows are independent.

Where pickup boxes live

In a track JSON file, the pickups array is just a list of world-space [x, y, z] triples:

{
  "pickups": [
    [14, 14, 1.0],
    [-14, -14, 1.0]
  ]
}

In the in-app editor, + Pickup arms the place tool — the next ground click drops one. See Modding → Tracks.