game.mcc

{
  "name": "addupgrade",
  "base": "",
  "fields": [
    {
      "name": "user",
      "type": "name"
    },
    {
      "name": "current_level",
      "type": "uint64"
    },
    {
      "name": "cost_of_upgrade",
      "type": "asset"
    }
  ]
}