Monster creation

A user has suggested improving this page or section as follows:

"How does the game decide whether or not to create a monster in the first place? And where to place it?"

The normal mechanism of monster creation, responsible for the vast majority of monsters in NetHack, is used when the game wants to create an unspecified opponent of adequate difficulty for the player.

When this occurs, each eligible monster has a probability equal to its effective monster frequency divided by the sum of the monster frequencies of every eligible monster. This may be thought of as generating a list of all such monsters with each appearing as many times as its frequency, and then choosing at random hence. A monster is eligible if it:

• Is no greater in difficulty than the average of the level's difficulty and the player level
• Is no lower in difficulty than one-sixth that of the current level's difficulty
• Is neither unique nor marked as not randomly generated (G_NOGEN)
• Is not genocided or extinct
• If you are on the rogue level:
  • Is represented by an upper case letter
• If you are in Gehennom:
  • Is not Lawful
  • Is not marked as not generated in Gehennom (G_NOHELL) (e.g. winter wolf)
• If you are not in Gehennom:
  • Is not marked as only generated in Gehennom (G_HELL) (e.g. hell hound)
• If you are on the Plane of Water:
  • Is a swimmer
• If you are on the Plane of Fire:
  • Has fire resistance
• If you are on the Plane of Air:
  • Is flying, whirly, floating, amorphous or non-corporeal
  • Is not a trapper or lurker above

See Also

• demons#demons summoning demons
• summon nasties
• summon insects
• polymorph
• spellbook of create monster
• wand of create monster
• scroll of create monster
• special rooms
• special level