Differenzler

Differenzler or Differenz-Jass is a 3-4 player trick taking game in which players predict how many trick points they can win. It's popular enough to merit its own weekly TV show, Samschtig-Jass on Schweizer Radio und Fernsehen.

Mostly from David Parlett's The Penguin Book of Card Games:

Deal three batches of three cards to four players, or four batches of three to three players, and turn the last for trumps. Melds don't count, only-trick points, which are the usual 157. Each in turn [starting with Forehand] bids to win an exact number of trick-points. Play as at Handjass. And the end of play, each scores the difference between what he or she bid and what he or she took. The winner is the player with the lowest score after 12 deals. A player who fulfills his or her bid exactly deducts 10 points from his or her total, provided that he or she won at least one trick.

Variant: Players may instead keep their bids secret by writing them down.