Make an async link
An async link is something you can share with players that creates a solo game for them with the parameters you give here. When they click it, they're brought right into a private room with these settings.
This lets everyone play the same board, just by themselves, like we do for weekly async games on the discord.
I'll make this a bit more user friendly later, but best thing to do is probably to open a solo room so you can see the card. Copy/paste the seed number out of the room over to here, then select the challenge you want to force on everyone with the drop down.
(when you get the link, right click and "copy link", since clicking it will bring you straight into a room made just for you)