tools-unity-gameplay-ability-system

Gameplay Ability System (GAS)

Overview

The Gameplay Ability System provides a framework for abilities, effects, attributes, and gameplay tags. This skill covers safe implementation patterns and common pitfalls.

When to Use

• Implementing combat abilities
• Managing gameplay effects (buffs, debuffs, damage)
• Attribute-based character stats
• Tag-based gameplay queries
• Status effect systems

Core Components

Component Hierarchy

AbilitySystemComponent (ASC)
├── Granted Abilities[]
├── Active Effects[]
├── Attribute Sets[]
└── Owned Tags[]

AbilitySystemComponent

public class AbilitySystemComponent : MonoBehaviour
{
    private List<GameplayAbilitySpec> _grantedAbilities = new();
    private List<ActiveGameplayEffect> _activeEffects = new();
    private Dictionary<string, AttributeSet> _attributeSets = new();
    private GameplayTagContainer _ownedTags = new();
    
    public IReadOnlyList<GameplayAbilitySpec> GrantedAbilities => _grantedAbilities;
    public IReadOnlyList<ActiveGameplayEffect> ActiveEffects => _activeEffects;
    public GameplayTagContainer OwnedTags => _ownedTags;
}

Abilities

Ability Specification

[CreateAssetMenu(menuName = "GAS/Ability")]
public class GameplayAbilitySO : ScriptableObject
{
    [SerializeField] private string _abilityId;
    [SerializeField] private GameplayTagContainer _abilityTags;
    [SerializeField] private GameplayTagContainer _activationBlockedTags;
    [SerializeField] private GameplayTagContainer _activationRequiredTags;
    [SerializeField] private GameplayTagContainer _cancelAbilitiesWithTags;
    [SerializeField] private float _cooldownDuration;
    [SerializeField] private GameplayEffectSO[] _costEffects;
    [SerializeField] private GameplayEffectSO[] _applyEffects;
    
    public bool CanActivate(AbilitySystemComponent asc)
    {
        // Check cooldown
        if (asc.HasActiveEffectWithTag(_cooldownTag))
            return false;
        
        // Check blocking tags
        if (asc.OwnedTags.HasAny(_activationBlockedTags))
            return false;
        
        // Check required tags
        if (!asc.OwnedTags.HasAll(_activationRequiredTags))
            return false;
        
        // Check cost
        return CanPayCost(asc);
    }
}