The Lab

- Run: top speed 340 px/s, 70 ms to reach it, 60 ms to stop. Keep 85% of that acceleration in the air.
- Jump: 150 px high, 360 ms to the top. Derive gravity as 2h/t² and jump speed as 2h/t, so height and time stay independent.
- Fast fall: multiply gravity by 1.7 on the way down.
- Variable jump height: if the button is released while rising, multiply gravity by 2.6 until the apex.
- Apex hang: while jump is held and vertical speed is under 70 px/s, multiply gravity by 0.50.
- Coyote time: 100 ms after leaving a ledge.
- Jump buffer: 120 ms before landing.
- Corner correction: nudge a rising character up to 8 px around a corner it clips.
- Squash and stretch: squash on landing in proportion to fall speed, stretch while airborne, keep the area constant, settle with a spring.
- Follow-through: a scarf on a rope simulation, pinned at the neck, dragged by run speed.
- Particles: dust at the feet on every landing, scaled by fall speed.
- Hit stop: freeze the action for 85 ms on a stomp, keeping the camera and particles alive.
- Screen shake: a decaying trauma value, with offset equal to trauma squared and smooth noise, not random jumps. Include a setting to reduce it.
- Camera lookahead: lead the camera up to 200 px in the direction of travel, easing into place rather than snapping.
- Run physics on a fixed 120 Hz timestep, so the jump is the same on any display.