If you want to jump in, go right ahead! The gist is, pick 10 monsters and build a mini setting around them. How do they interact? Who was there first? Who wants what from who?
If you do one, tag it #tenmonstersetting
Here's a few more!
And a new one: https://savemycampaign.wordpress.com/2019/05/13/10-monster-setting/
If you need a bit more help Chris Hall came up with this:
After I suggested this Chris Hall came up with this handy list:
Pick a semi-intelligent humanoid (could be goblins, apemen, subhumans, etc.). Pick an undead. Pick an ancient fey race. Pick a giant/ogre/troll race. Pick a type of great wyrm or lizard. Pick something aerial. Pick something to lurk in the water. Pick something from another dimension (demon, gith, illithid). Pick a classic creature from mythology (medusa, satyr, minotaur, etc.). Pick some foul crawly thing that infests the underworld. Something like that. Then I’d give each a twist.