Unityでゲームのガチャ機能の作成方法を完全解説

using UnityEngine;

public enum Rarity
{
    None = 0,
    Normal = 1,
    Rare = 2,
    SuperRare = 3,
    Legend = 4,
    Max = 5,
}

[CreateAssetMenu(menuName = "Gacha/GachaItem")]
public class GachaItem : ScriptableObject
{
    public string itemName;
    public Rarity rarity;        // レア度（例: 1〜5）
    public Sprite icon;
    public int weight;        // 排出確率用の重み
}

using System.Collections.Generic;
using UnityEngine;

public class GachaSystem : MonoBehaviour
{
    [Header("ガチャから排出されるアイテムリスト")]
　　[SerializeField] private List<GachaItem> gachaItems_N;
　　[SerializeField] private List<GachaItem> gachaItems_R;
　　[SerializeField] private List<GachaItem> gachaItems_SR;
　　[SerializeField] private List<GachaItem> gachaItems_LD;

　　// ガチャ１回引くのに必要なお金
    [SerializeField]
    private int gachaCost = 5;

    // お金
    private int money = 100;

    public void DropGacha()
    {
        // お金チェック
        if (money < gachaCost)
        {
            Debug.Log("お金が足りません");
            return;
        }

        // お金払う
        money -= gachaCost;

        // 抽選
        GachaCharacter result = Lottery();
        Debug.Log($"ガチャ結果: {result.itemName}（★{result.rarity}）");

        // TODO: 演出・UI表示・所持リスト追加
    }

    private GachaItem Lottery()
    {
        float rand = Random.value;
        Debug.Log(rand);
        // LD 3%
        if (rand < 0.03f)
        {
            return gachaItems_LD[Random.Range(0, gachaItems_LD.Count)];
            // PU 75%
            //if (Random.value < 0.75f)
            //    return ssrPickupCards[Random.Range(0, ssrPickupCards.Count)];
            //else
            //    return ssrNormalCards[Random.Range(0, ssrNormalCards.Count)];
        }

        // SR 18%
        if (rand < 0.21f)
        {
            return gachaItems_SR[Random.Range(0, gachaItems_SR.Count)];
        }

        // SR 29%
        if (rand < 0.50f)
        {
            return gachaItems_R[Random.Range(0, gachaItems_R.Count)];
        }

        // R 50%
        return gachaItems_N[Random.Range(0, gachaItems_N.Count)];
    }
}