[
    {
        "level": 1,
        "spawnInterval": 2000,
        "enemyTypes": ["grunt"],
        "enemyMultiplier": 1.0
    },
    {
        "level": 2,
        "spawnInterval": 1800,
        "enemyTypes": ["grunt", "brute"],
        "enemyMultiplier": 1.2
    },
    {
        "level": 3,
        "spawnInterval": 1600,
        "enemyTypes": ["grunt", "brute", "tank"],
        "enemyMultiplier": 1.5
    }
]