05 — 2D Platformer Movement

Run Tools → Input System Starter Kit → Create 2D Platformer Demo in an empty scene, press Play, and feel it: run with A/D or the stick, jump with Space — tap for a hop, hold for full height. Then open Scripts/Platformer2D/PlayerController2D.cs and follow along.

The input layer (the part this course is about)

• Move is polled in Update: moveAction.ReadValue<Vector2>().x. Horizontal movement is a state ("how far is the stick?"), so polling fits.
• Jump uses events: performed stamps a jump-buffer timer, canceled cuts upward velocity for variable jump height. Jumping is a moment, so events fit.

That pairing — poll the values, subscribe to the moments — is the pattern you'll reuse in every genre.

The physics layer (quick notes for completeness)

• Input is read in Update (every rendered frame, so no missed presses), but velocity is applied in FixedUpdate (physics steps). Passing values from one to the other via fields is the standard bridge.
• Grounding uses a thin Physics2D.BoxCast under the collider. The demo player sits on the Ignore Raycast layer so the cast can't hit the player itself — a classic gotcha, solved in data rather than code.
• Rigidbody2D settings that matter: Freeze Rotation ✓, Collision Detection Continuous, gravity scale ~3.5 (real gravity feels floaty in platformers).

The game feel layer (why it doesn't feel like a school project)

• Coyote time (0.1 s) — you can jump for a moment after running off a ledge.
• Jump buffering (0.1 s) — pressing jump just before landing still jumps.
• Jump cut — releasing early multiplies upward velocity by 0.5.

Comment each of these out (they're clearly marked) and play again — students immediately understand why every good platformer does this.

Exercises

1. Wire the Dash you added in 03 - The Input Actions Asset: find the action in OnEnable, subscribe performed, and impulse body.linearVelocity in the facing direction. Bonus: a cooldown timer.
2. Change Move's gamepad binding to add a Processor (select the leftStick binding → Properties → Processors → Stick Deadzone) and raise the deadzone until drift stops on an old controller — no code, that's the point.
3. Add a Crouch action bound to S/left-stick-down that halves the collider height.

Compare with the community approaches in this video platformer series and this written one.

Next: 06 - First-Person and Weapon Switching