[
  {
    "id": "fortress_guardian",
    "race": "fortress",
    "tier": 1,
    "cost_minerals": 100,
    "cost_gas": 0,
    "hp": 350,
    "armor_type": 2,
    "attack_type": 0,
    "damage": 12,
    "attack_speed": 0.8,
    "range": 2.5,
    "move_speed": 120.0,
    "upgrades_to": "fortress_bastion",
    "strong_vs_waves": [1, 2, 3, 5]
  },
  {
    "id": "fortress_bastion",
    "race": "fortress",
    "tier": 2,
    "cost_minerals": 200,
    "cost_gas": 40,
    "hp": 700,
    "armor_type": 2,
    "attack_type": 0,
    "damage": 28,
    "attack_speed": 0.7,
    "range": 3.0,
    "move_speed": 110.0,
    "upgrades_to": "fortress_citadel",
    "strong_vs_waves": [7, 10, 13, 16]
  },
  {
    "id": "fortress_citadel",
    "race": "fortress",
    "tier": 3,
    "cost_minerals": 400,
    "cost_gas": 100,
    "hp": 1400,
    "armor_type": 2,
    "attack_type": 0,
    "damage": 55,
    "attack_speed": 0.6,
    "range": 3.5,
    "move_speed": 100.0,
    "upgrades_to": "",
    "strong_vs_waves": [20, 22, 25, 29]
  }
]