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Unity Beginner Project: Build a 2D Top-Down Adventure Controller - Game Development Guide | Checkpoint Zero

Unity Beginner Project: Build a 2D Top-Down Adventure Controller

In this guide you will build the foundation of a small 2D adventure game in Unity. By the end, you will have a player that moves smoothly, a camera that follows, collectible keys, and a locked gate that opens when the player has the key.

This is a good first Unity project because it teaches the loop used in many games:

Read player input.
Move a character through the world.
Detect nearby objects.
Change game state when something happens.
Give the player feedback.

What You Will Make

The final scene is simple but meaningful: a player explores a small room, picks up a key, walks to a gate, and opens it. You can later expand this into a dungeon, farming game, RPG town, or survival prototype.

Step 1: Create the Unity Project

Open Unity Hub and create a new project:

Template: 2D
Name: TopDownAdventure
Location: anywhere inside your projects folder

When the project opens, create these folders in the Project window:

TEXT
1Assets/2  Art/3  Prefabs/4  Scenes/5  Scripts/

Save the current scene as:

TEXT
1Assets/Scenes/Main.unity

You do not need polished art. Use simple colored squares for now. Beginners often get stuck searching for assets before they understand the system. Build the system first.

Step 2: Create the Player

In the Hierarchy:

Right-click and choose 2D Object > Sprites > Square.
Rename it to Player.
Set its color to blue in the Sprite Renderer.
Add a Rigidbody2D.
Add a CapsuleCollider2D or BoxCollider2D.

Set the Rigidbody2D:

Gravity Scale: 0
Freeze Rotation Z: enabled
Collision Detection: Continuous if your player moves fast

The player should not fall because this is a top-down game.

Step 3: Add Movement Code

Create a script named PlayerMovement.cs in Assets/Scripts.

CSHARP
1using UnityEngine;2 3public class PlayerMovement : MonoBehaviour4{5    [SerializeField] private float moveSpeed = 5f;6 7    private Rigidbody2D body;8    private Vector2 input;9 10    private void Awake()11    {12        body = GetComponent<Rigidbody2D>();13    }14 15    private void Update()16    {17        input.x = Input.GetAxisRaw("Horizontal");18        input.y = Input.GetAxisRaw("Vertical");19        input = input.normalized;20    }21 22    private void FixedUpdate()23    {24        body.MovePosition(body.position + input * moveSpeed * Time.fixedDeltaTime);25    }26}

Attach this script to the Player.

Press Play and test:

WASD or arrow keys should move the player.
Diagonal movement should not be faster because input.normalized keeps the vector length at 1.
The Rigidbody2D moves in FixedUpdate, which is better for physics movement.

Step 4: Build a Simple Room

Create walls using square sprites:

Right-click 2D Object > Sprites > Square.
Rename it Wall.
Scale it into a long rectangle.
Add a BoxCollider2D.
Duplicate it to make four walls.

Make sure the walls have colliders. Your player should not pass through them.

If the player slides strangely, check:

Player has Rigidbody2D.
Walls have Collider2D but no Rigidbody2D.
Player Rigidbody2D has Gravity Scale 0.

Step 5: Make the Camera Follow the Player

Create CameraFollow.cs.

CSHARP
1using UnityEngine;2 3public class CameraFollow : MonoBehaviour4{5    [SerializeField] private Transform target;6    [SerializeField] private float smoothTime = 0.12f;7 8    private Vector3 velocity;9 10    private void LateUpdate()11    {12        if (target == null) return;13 14        Vector3 targetPosition = new Vector3(15            target.position.x,16            target.position.y,17            transform.position.z18        );19 20        transform.position = Vector3.SmoothDamp(21            transform.position,22            targetPosition,23            ref velocity,24            smoothTime25        );26    }27}

Attach this to the Main Camera and drag the Player into the Target field.

Use LateUpdate because the player has already moved for the frame. That prevents tiny camera jitter.

Step 6: Create a Key Pickup

Create a yellow square sprite and rename it Key.

Add:

CircleCollider2D
Enable Is Trigger

Create PlayerInventory.cs.

CSHARP
1using UnityEngine;2 3public class PlayerInventory : MonoBehaviour4{5    public bool HasKey { get; private set; }6 7    public void GiveKey()8    {9        HasKey = true;10        Debug.Log("Picked up key.");11    }12}

Attach PlayerInventory to the player.

Create KeyPickup.cs.

CSHARP
1using UnityEngine;2 3public class KeyPickup : MonoBehaviour4{5    private void OnTriggerEnter2D(Collider2D other)6    {7        PlayerInventory inventory = other.GetComponent<PlayerInventory>();8        if (inventory == null) return;9 10        inventory.GiveKey();11        Destroy(gameObject);12    }13}

Attach KeyPickup to the key object.

Press Play and walk into the key. It should disappear and log a message.

Step 7: Create a Locked Gate

Create a red rectangle sprite and rename it LockedGate.

Add:

BoxCollider2D
Leave Is Trigger disabled so it blocks the player.

Create LockedGate.cs.

CSHARP
1using UnityEngine;2 3public class LockedGate : MonoBehaviour4{5    [SerializeField] private string lockedMessage = "Find the key first.";6    [SerializeField] private string openedMessage = "Gate opened.";7 8    private void OnCollisionEnter2D(Collision2D collision)9    {10        PlayerInventory inventory = collision.gameObject.GetComponent<PlayerInventory>();11        if (inventory == null) return;12 13        if (!inventory.HasKey)14        {15            Debug.Log(lockedMessage);16            return;17        }18 19        Debug.Log(openedMessage);20        Destroy(gameObject);21    }22}

Attach it to the gate.

Now test both paths:

Touch the gate before collecting the key. It should stay locked.
Pick up the key, then touch the gate. It should disappear.

Step 8: Turn It Into a Tiny Game Loop

Right now the system works, but it needs structure. Add a second room behind the gate and place a green square named Exit.

Create LevelExit.cs.

CSHARP
1using UnityEngine;2 3public class LevelExit : MonoBehaviour4{5    private void OnTriggerEnter2D(Collider2D other)6    {7        if (!other.CompareTag("Player")) return;8        Debug.Log("Level complete.");9    }10}

Set the Player tag to Player, add a trigger collider to the exit, and attach the script.

You now have a complete tiny objective:

Explore.
Find key.
Unlock gate.
Reach exit.

Step 9: Beginner Debug Checklist

If something does not work, check these in order:

Is the script attached to the correct GameObject?
Is the collider set to trigger only when the script expects a trigger?
Does the player have the required component?
Is the Rigidbody2D on the moving object, not the wall?
Did you save the scene?
Is the GameObject active in the Hierarchy?

What To Add Next

Good next upgrades:

Add a UI text prompt instead of Debug.Log.
Add two keys and two gates.
Add a simple enemy that resets the room.
Add a coin counter.
Add scene loading when the player reaches the exit.

The important lesson is that Unity gameplay is usually many small components talking to each other. Keep each component responsible for one job, and your projects will stay easier to expand.

Unity Beginner Project: Build a 2D Top-Down Adventure Controller

Unity Beginner Project: Build a 2D Top-Down Adventure Controller

What You Will Make

Step 1: Create the Unity Project

Step 2: Create the Player

Step 3: Add Movement Code

Step 4: Build a Simple Room

Step 5: Make the Camera Follow the Player

Step 6: Create a Key Pickup

Step 7: Create a Locked Gate

Step 8: Turn It Into a Tiny Game Loop

Step 9: Beginner Debug Checklist

What To Add Next

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