Guide 7 — The Magnet

Amarion Wilson

What you're building

A 2D side-scroller in the spirit of the first Sonic. The Magnet isn't actually a magnet — he's a guy in a suit with magnet gloves that pull metal toward him. You fight your way through masked criminals to a boss called Blaster.

You said in your pitch you're new to game design and wanted something simple. This guide is built around that: the core game is a platformer with enemies, which you'll have running in about an hour, and the magnet is a mechanic you bolt on afterward. If you stop after section 6 you still have a complete game.

You also already have three sprites drawn — The Magnet, Blaster, and the masked criminal — which puts you ahead of most of the class. Use them from the start. Building against real art is more motivating than grey boxes.

Time: about two hours for the platformer, another hour for the magnet.

1. Before you start

• Finish Guide 0.
• Read Guide B §B1 (player) and §B4 (enemy).
• One new input action: Magnet. See section 7.

2. Scripts you'll use

Core — Guide B §B1, §B2
PlayerController2D · PlayerAnimatorBridge · Health · DamageOnContact · Checkpoint · RespawnManager · CameraTargetAssigner · SceneLoader · GameManager · AudioManager · HUDController · ParallaxBackground

Combat (Tier 2)
Team · Hurtbox · Hitbox · Knockback · MeleeAttack · EnemyPatrol · Projectile · ProjectileShooter · BossController · BossArenaTrigger

The magnet (Tier 3)
MagnetPull · MetalObject

Level (Tier 4)
Breakable · KillZone

3. Build The Magnet

Follow Guide B §B1 with your Magnet sprite, then set:

Add Knockback: Stun Duration 0.25, Resistance 0.

The two children

Hurtbox — trigger collider slightly smaller than the sprite, Hurtbox component with Team = Player, object layer Hurtbox.

AttackHitbox — trigger collider positioned in front of him, Hitbox component:

Object layer Hitbox. Untick the GameObject checkbox so it starts disabled.

Because the hitbox is a child, it flips automatically when The Magnet turns around. That's why it goes on a child rather than the root.

Melee attack

Add MeleeAttack to the player root:

Those three timings add up to 0.4 seconds. When you make an attack animation later, match its length to 0.4 — or change these numbers to match your animation. A 1-second swing animation with a 0.4-second script makes the character flail after the hit is gone.

4. Build the masked criminal

Follow Guide B §B4 with your criminal sprite:

Children:

• WallCheck (in front, chest height) and LedgeCheck (in front, below the feet) → drag both into EnemyPatrol
• Hurtbox — Team = Enemy, layer Hurtbox
• BodyHitbox — Target Team = Player, Damage 1, Repeat Delay 1, layer Hitbox, left enabled

Save as a prefab. This is the enemy you'll place most.

The ledge check matters

Without LedgeCheck, criminals walk off platforms and die in pits, which looks broken. Put the empty child slightly in front of the feet and slightly below them, and set Check Distance to about 0.15.

5. Build the level

• Tilemap or sprites for ground, all on Layer → Ground, with colliders
• A wide KillZone (trigger collider + KillZone component) under everything
• Checkpoint prefabs (trigger + Checkpoint) at intervals
• A LevelExit at the end (trigger + LevelExit, Requirement None, Destination Next In Build)
• Camera per Guide B §B3, with a confiner

Prototype with grey rectangles, then swap in art. Your sprites are pixel art — set their Filter Mode to Point (no filter) and Compression to None in the import settings, or they'll look blurry.

6. Playtest the platformer

Stop and play before adding the magnet. You should have:

1. The Magnet runs and jumps
2. Attack swings and kills a criminal in two hits
3. Criminals patrol and turn at ledges and walls
4. Touching a criminal costs a heart
5. Dying respawns you at the last checkpoint

If all five work, you have a game. Everything from here is enhancement.

7. Add the magnet gloves

Now the fun part.

First: the input action

Open your input actions asset (Guide 0 §6):

1. Under the Player map, click + → name it exactly Magnet
2. Action Type Button
3. Add Binding → Path → Listen → click the right mouse button (or pick a key like Q)
4. Save Asset

Then: the hold point

Right-click Player → Create Empty, name it HoldPoint. Position it about one unit in front of the chest. This is where pulled objects come to rest.

Then: the component

On Player, add MagnetPull:

How it plays

Hold Magnet to pull metal objects toward you. When one reaches your hold point it snaps into your hands. Press Attack while holding to throw it. Release Magnet to drop it.

The orange gizmo shows the radius and cone when the player is selected. Use it to check the cone points the right way.

Optional: the beam

Make a prefab with just a Line Renderer (2 positions, width 0.05, a material assigned — a Line Renderer with no material renders bright magenta). Drag it into Beam Prefab and you'll get a visible line to each pulled object. Cheap and it makes the mechanic legible.

8. Build metal objects

A metal crate

1. Empty GameObject MetalCrate + Sprite Renderer.
2. Rigidbody2D — Dynamic, Mass 1, Linear Damping 1.
3. Box Collider 2D (solid, not a trigger).
4. Layer → Metal ← without this, nothing happens.
5. MetalObject component:

6. Also add a DamageOnContact:

7. Untick the DamageOnContact component's checkbox so it starts off, then drag it into MetalObject's Damage While Flying slot.

Now the crate is harmless lying on the ground and dangerous while flying. That's the whole trick.

8. Save as a prefab.

A breakable metal barrier

Same as above, plus:

• Health — Max Health 3, Destroy On Death ✗, Invulnerability 0
• Breakable — Min Damage To Break 2, with Loot Prefabs if you want it to drop something
• A Hurtbox child with Team = Neutral (so anything can hit it)

Min Damage To Break 2 means your fist (Damage 1) won't open it but a thrown crate (Damage 2) will. That's a puzzle made from two numbers.

9. Build Blaster

Your boss shoots. BossController assembles him from parts.

1. Empty GameObject Blaster, Tag → Enemy, your Blaster sprite, Rigidbody2D, Capsule Collider 2D.
2. Add:
   • Health — Max Health 20 · Invulnerability 0 · Destroy On Death ✗
   • Knockback — Resistance 1
   • BossController — Start Automatically ✗ · Face Player ✓
3. Child Hurtbox — Team = Enemy, layer Hurtbox.
4. Child FirePoint — an empty in front of his gun.
5. Add ProjectileShooter to the Blaster root:

The bullet prefab

Sprite + Rigidbody2D (Gravity Scale 0) + Circle Collider 2D (Is Trigger ✓) + Projectile:

The phases

On BossController, add two phases:

Phase 1 — Health Percent 100, Rest Between Attacks 1.5

Phase 2 — Health Percent 50, Rest Between Attacks 0.8

6. Add a BossArenaTrigger at the arena door, drag Blaster in, and put a wall object in Barriers.

A magnet-flavoured boss idea

Here's something your mechanic makes possible that nobody else in the class can do: give Blaster a metal shield plate as a separate object on the Metal layer, positioned in front of him, with a collider that blocks your attacks. The player has to pull the shield off with the magnet before they can hurt him.

To build it: a child object of the arena (not of Blaster, so it can be pulled away), on the Metal layer, with a Rigidbody2D and a MetalObject. Put Blaster's Hurtbox behind it. It's a few minutes of work and it makes the boss about your mechanic rather than just a health bar.

10. The HUD

1. Canvas → three heart Images in a row, top-left (Heart1, Heart2, Heart3).
2. Empty child HUD with HUDController.
3. Add all three hearts to the Heart Icons list, and assign Heart Full and Heart Empty sprites.

11. Wire it up

12. Magnet playtest

With a metal crate in the level:

1. Hold Magnet near a crate — it slides toward you. If nothing moves: is the crate on the Metal layer? Is Metal Layer set on MagnetPull? Is the crate a Dynamic Rigidbody2D?
2. The crate snaps into your hands when it gets close.
3. Press Attack while holding — it flies forward.
4. A thrown crate hurts a criminal, a resting one doesn't.
5. The cone works — face away from a crate and it shouldn't pull.

If crates orbit around you rather than settling, lower Pull Force to 20. If they crawl, raise it. This one genuinely needs tuning by feel.

13. Then add

1. More level. Your systems are done after section 9.
2. Animation — Guide B §B6, plus an Attack trigger. You have sprites; a four-frame walk and a two-frame swing goes a long way.
3. ParallaxBackground — a city skyline. Depth 0.2 for distant buildings, 0.5 for closer ones.
4. A criminal with a metal weapon you can yank away: give the weapon its own Rigidbody2D on the Metal layer. Advanced, but very on-theme.
5. Breakable walls that need a thrown crate to open.
6. Sound: a magnetic hum while pulling, a clang on throw, punch impacts.

14. Design notes for your game specifically

You said you wanted something simple, and this is the right instinct. A short, finished, polished level beats an ambitious unfinished one every time. If you get the platformer working and add nothing but the magnet, you'll have made a real game.

Use the magnet for puzzles, not just damage. Throwing crates at enemies is fine, but the mechanic gets interesting when it's the only way past something: a crate you have to pull down to stand on, a barrier that needs a thrown object, a boss shield you have to strip. One good puzzle beats ten thrown crates.

The suit is a good excuse. He's not a superhero, he's a guy with equipment — which means the gloves can have limits (range, cone, how many objects) and those limits are the game. The cone angle in particular is worth keeping fairly narrow; pulling from all directions is less interesting than having to face what you want.

Two hits to kill a criminal is right. One hit and there's no combat; three and it drags. If you add tougher enemies later, add them alongside the weak ones rather than replacing them.

15. Common problems

16. Checklist

• Player with Hurtbox (Team Player) and disabled AttackHitbox (Target Enemy)
• MeleeAttack with the hitbox assigned
• Criminal prefab with patrol sensors, Hurtbox, BodyHitbox
• Level with ground, checkpoints, kill zone, exit
• Section 6 playtest passes before you add the magnet
• Magnet input action added
• HoldPoint child, MagnetPull with Metal Layer set
• Metal crate on the Metal layer with MetalObject + disabled DamageOnContact
• Blaster with two phases, ProjectileShooter in Manual mode, arena trigger
• Hearts on a Canvas
• All six events wired