Repost from ravignir (from 23/3/2022):

I am happy to announce the Custom Puzzle Contest! 
Submit your puzzle to #puzzle-contest# channel!
The best puzzles will be added into the game!

• Your puzzle entry should have a form of an image - you can use test mode and then edit your screenshot accordingly. 
• Your puzzle must be 100% legal, i.e. the situation must be achievable in a regular game.
• The solution can not be luck based, it has to work 100% of time.
• Your puzzle should have just one solution, but it is fine if there are multiple solution solve it, given they are not completely different.
• You can submit any number of puzzles.
• Any solution to submitted puzzle must be hidden behind the spoiler. Don't post the solution until someone solves the puzzle.
• You have one month to submit your puzzle entries (it may change depending on how many entries there will be)

Puzzles are card decks puzzles, let see some examples from YT: