Enable cheat mode, then use the entities code to get a list of the creatures in the location you are currently in. Usually, when you try to spawn a creature, you have to use the noclip code to levitate in the air and spawn the creature nowhere near any objects. If a part of a spawned creature is spawned within a wall, ceiling, or another creature, the game crashes. However, if you enable the developer 0 code, the game continues even if a spawned creature is stuck, but the creature has yellow dots around it. Also, bind the spawn commands to unused keyboard keys; for example bind X "Impulse 76" or bind y "give monster_scientist". The impluse 76 code works everywhere, and the hostile grunts created with it are easy to place where you want them; as they appear in front of you, rather than above. Now, enable the noclip code and fly around pressing the bound keys. Watch as Barney's Aliens and Grunts battle it out while Scientists run around being slaughtered.