Protospiel is an event where you can bring a board or card game prototype to play with other designers, play testers, and publishers. It's a great way to break your game and to fix it. It doesn't matter what level of polish your game has. Many games are made right on the spot at Protospiel using the
free prototyping materials provided by The Game Crafter. But there are also many games there that are just doing final testing just before they are published or put out on Kickstarter.
Note: Thursday, November 29th is Crafter Con, which is a special event and either requires attendees to have a "Crafter Con Only" badge or a "Crafter Con + Protospiel" badge. (See https://tabletop.events/conventions/protospiel-madison-2018/pages/craftercon for details). The regular Protospiel Madison event starts on Friday, Nov 30 and ends Sunday, Dec 2.