My idea is to have a option to create a custom map, like for private use only, like with friends!
You could send it to OOO for comfirmation on going public to have more variety in maps, and u could have a slot/selection in the missions bar just for custom maps. they wouldn't give as much crowns, but it would be fun!
and you can ,limit it so only some ranks can go through it!
Tell ma wat u think!
Check out this thread that Fehzor made a few years back.
I believe a custom level creator would be fun. Here's my thoughts on how a level editor could work.
These are both more in-depth and take a lot more into consideration.