So, I had an idea for a platformer level collab.
First, everyone writes a prompt for a level. These prompts will be subject to quality control.

Then, we’ll assign each prompt a difficulty. There will be 3 difficulties:

• Easy: hard to Insane/Easy Demon
  
• Medium: Easy/Medium Demon to Insane Demon
  
• Hard: Extreme Demon

Then, everyone gets a random prompt and makes their own level based on that prompt.

Finally, there will be a level that combines everyone's level into 1 (this will be referred to as a heart-side). There will be 3 heart-sides, each corresponding to a difficulty. There, everyone will create one room that's based on their level. This level should end up being much harder than the other levels, but should be reasonable for their respective difficulty.

I'm not starting one, I’m just sharing my idea for one. The inspiration for this idea obviously comes from modded Celeste collabs (particularly the Secret Santa Collabs).