Whilst the idea of randomly generated monsters is a nice one, the monsters we have are all more or less identical (there are a few ones which are different, like shooting a projectile, but all the projectile-shooters are all more or less identical), and become dull quickly. So I was thinking, what if instead you create a range of preset monsters, all with their own custom AIs, then just randomize the sprites and stats (although the stat randomization is controlled by the monster type)? This way, you sacrifice a bit of randomness for monsters that feel more alive and function better, plus the addition of controlling how child variants (and any other variants, if they undergo metamorphosis) work (and then child variants could be the only capturable creatures, instead of "small creatures"). For example: You have a quadruped monster which shoots spikes from its tail. Currently the AI tells says "walk until you see a player, then attack", making a monster that shoots spikes whilst just sitting there, being beaten to death with a hammer. With this addition, the "quadruped-spike-tail" monster could be told to run away from players when they get close, only using a melee attack when they are cornered or run too far. Or when cornered, it could start firing all of its spikes rapidly as a last resort before going into melee attacks. As a bonus, the monster could also explode into spikes after a few seconds upon death. The child variant of the quadruped could be unable to fire spikes or explode into spikes, instead just run away from the player. You can also have really strange creatures, such as creatures which upon death explode into a tentacle abomination akin to The Thing, or are a slime-like thing which splits into two upon death (like Mother Slimes in Terraria), or can move via teleportation. Edit: If preset monsters can be told to spawn only within randomly generated microbiomes (things like monster dens) you can have randomly generated humanoid tribes, because there cannot only be 9(?) intelligent beings in the universe, when every planet (with the exception of the incredibly rare barren planets) has life.