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Build a Responsive 2D Platformer Character Controller

Code a tight 2D platformer controller with acceleration, variable jump height, coyote time and jump buffering, the tricks behind great game feel.

By Pixelfork Team1 min read

Cover illustration: Exploring the Unity game engine, a beginner's guide, with a stone tower in a mountain valley

Great platformers feel good because of small, invisible tricks. Let's build a controller that includes them.

Acceleration, not instant speed

Instant movement feels stiff. Ease velocity toward the target speed instead:

const target = input.x * MAX_SPEED;
const rate = onGround ? GROUND_ACCEL : AIR_ACCEL;
velocity.x = moveTowards(velocity.x, target, rate * dt);

Variable jump height

Let players control jump height by cutting upward velocity when they release the button early:

if (jumpReleased && velocity.y > 0) {
  velocity.y *= 0.5;
}

Coyote time

Allow a jump for a few frames after walking off a ledge. Players believe they pressed jump in time, so let them.

coyoteTimer = onGround ? COYOTE_TIME : coyoteTimer - dt;

Jump buffering

If the player presses jump slightly before landing, remember it and jump as soon as they touch the ground.

if (jumpPressed) bufferTimer = BUFFER_TIME;
else bufferTimer -= dt;

if (bufferTimer > 0 && coyoteTimer > 0) {
  velocity.y = JUMP_SPEED;
  bufferTimer = 0;
  coyoteTimer = 0;
}

Heavier falling

Increase gravity when falling for a snappy arc:

const g = velocity.y < 0 ? GRAVITY * 1.8 : GRAVITY;
velocity.y -= g * dt;

Start with around 0.1 seconds for both coyote time and jump buffer, then tune by feel.

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