Don Q. and Sancho Pansa are surveying La Mancha. Each player places hidden markers on his/her side of the board. Some of these are positive, some are negative. Then the players take turns placing tokens on the board. Each time a token is placed, the opposing player has to reveal one marker. Only tokens facing three or more positive markers are counted towards the final score at the end of the game.
When a player believes that more than half of the final points have been scored, he/she can decide to play Don Q. From that moment on, all points count for Sancho Pansa. When all markers have been revealed, the player with most points is the winner.

(User summary by HilkMAN)

You can play this game online here: http://www.erlkoenig.ws/hrrg/receiver.php?do=SpecifyCodeInput&lang=1

There is also a link describing the rules online.