【Unity】コマンドライン引数で単一ビルドに複数ビルドの振る舞いをさせる ref: https://qiita.com/splas_boomerang/items/0bb9335111a596b6774f

file0.txt

./test.exe -mode 1

Test.cs

public class Test : MonoBehaviour
{
    void Start()
    {
        string[] args = System.Environment.GetCommandLineArgs();
        for (int i = 0; i < args.Length; ++i)
        {
            switch (args[i])
            {
                case "-mode":
                    int mode = 0;
                    if (i + 1 < args.Length && int.TryParse(args[i + 1], out mode))
                    {
                        // do something
                    }
                    break;
            }
        }
    }
}