actor Alienspawner : RandomSpawner 3001 
{
    DropItem "AlienRunnerSpawner"
}

actor AlienRunnerSpawner : RandomSpawner
{
     Dropitem "AdultRunner", 256, 5
     Dropitem "AdultRunnerOnCeiling", 256, 3
     Dropitem "YoungRunner", 256, 3
}