Unity Weapon Strategy System

Small Unity prototype inspired by Twisted Metal. The focus is the Weapon System implemented with a Strategy pattern (polymorphism) so you can add new weapons without changing existing code.

Features

• Strategy-based weapons: a common Weapon abstraction with concrete weapons like FireWeapon and FrostWeapon.
• Plug-and-play: create a new weapon by subclassing Weapon and assigning an icon, name, amount and a bullet prefab.
• UI binding: minimal UIManager to show current weapon name, icon, and remaining ammo.
• Simple vehicle controller to move the car while testing weapons.
• Clean separation of concerns: WeaponSystem handles selection/usage, each Weapon handles how to fire.

Project Structure (scripts)

Scripts/
 ├─ Weapon.cs              # Base class (Strategy): name, amount, icon, bullet prefab; Use() & IncreaseAmount()
 ├─ FireWeapon.cs          # Concrete strategy (inherits Weapon)
 ├─ FrostWeapon.cs         # Concrete strategy (inherits Weapon)
 ├─ WeaponSystem.cs        # Manages current weapons, cycling, using, adding, UI updates
 ├─ Bullet.cs              # Moves forward; used by Weapon prefabs
 ├─ SimpleCarController.cs # WASD movement for quick testing
 └─ UIManager.cs           # Shows weapon name, ammo, icon

Design: Strategy Pattern

The Strategy is the Weapon base class:

public abstract class Weapon : MonoBehaviour
{
    public string displayName;
    public int amount;      // ammo/charges
    public Sprite icon;
    public Bullet prefab;   // projectile to spawn

    int _initialAmount;

    void Start() => _initialAmount = amount;

    public virtual void Use(Transform player)
    {
        amount--;
        var bullet = Instantiate(prefab);
        bullet.transform.position = player.position + Vector3.up;
        bullet.transform.forward  = player.forward;
    }

    public void IncreaseAmount() => amount += _initialAmount;
}

Concrete weapons (strategies) are simple subclasses (override Use if behavior differs):

public class FireWeapon : Weapon { /* override Use() to add fire effects, AoE, etc. */ }
public class FrostWeapon : Weapon { /* override Use() to add slow/freeze, etc. */ }

WeaponSystem owns the current list and delegates to the active strategy:

public class WeaponSystem : MonoBehaviour
{
    public UIManager UIManager;

    List<Weapon> _currentWeapons = new();
    int _currentWeaponIndex;

    void Start() => UIManager.ShowNothing();

    // Call this when picking up a weapon
    public void AddWeapon(Weapon weapon)
    {
        var existing = _currentWeapons.FirstOrDefault(w => w.GetType() == weapon.GetType());
        if (existing != null) existing.IncreaseAmount();
        else _currentWeapons.Add(weapon);
        UpdateUI();
    }

    public void UseCurrent(Transform player)
    {
        if (_currentWeapons.Count == 0) return;
        _currentWeapons[_currentWeaponIndex].Use(player);
        if (_currentWeapons[_currentWeaponIndex].amount <= 0)
            _currentWeapons.RemoveAt(_currentWeaponIndex);
        UpdateUI();
    }

    void UpdateUI()
    {
        if (_currentWeapons.Count > 0)
            UIManager.ShowCurrentWeapon(_currentWeapons[_currentWeaponIndex]);
        else
            UIManager.ShowNothing();
    }
}

How to Run

1. Open the project in Unity (the sample scene is Scenes/SampleScene.unity).

2. Press Play.

   • Drive with W / A / D (SimpleCarController).
   • Hook your input to WeaponSystem.UseCurrent() and to cycle weapons if needed.

3. The UI updates automatically through UIManager when the current weapon changes or ammo runs out.

➕ Adding a New Weapon (in 60 seconds)

1. Create a new script that inherits from Weapon (e.g., LaserWeapon.cs).

2. (Optional) Override Use(Transform player) for custom behavior (spread, homing, slow, AoE, status effects, etc.).

3. Create a Weapon prefab with:

   • the new Weapon component,
   • an icon,
   • displayName,
   • initial amount,
   • a Bullet prefab (or your own projectile).

4. Call WeaponSystem.AddWeapon(newWeaponPrefab) when the player picks it up.

Because it’s Strategy-based, new weapons don’t require changes to WeaponSystem.

UI

UIManager uses TextMeshPro and an Image to display:

• Name (displayName)
• Ammo (amount)
• Icon (icon)

Call UIManager.ShowCurrentWeapon(weapon) to refresh, or ShowNothing() when the player has none.

Notes & Next Steps

• The Bullet script is intentionally minimal (transform.forward * speed). Extend it with damage, lifetime, VFX, hit detection, etc.

• Consider adding:

  • Pickup trigger that calls WeaponSystem.AddWeapon(...)
  • Input bindings for cycle next/previous weapon
  • Cooldowns / charge types per weapon
  • Object pooling for bullets (performance)
  • Distinct VFX/SFX per concrete weapon

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