Kruistocht in Spijkerbroek is a tie-in with the children's adventure movie of the same name (Crusade in Jeans). It is an adaptation of the 1973 book by Thea Beckman and tells the story of Dolf Wega, a 16-year-old boy who volunteers for an experiment with a time machine, but ends up in the 13th century. Set in 1212, he joins the Children's Crusade where a group of children is lead to liberate Jerusalem. A factual children's crusade is still a subject of debate among historians, but in Beckman's fiction the children are actually meant to be sold as slaves instead. Dolf knows the outcome and tries to save as many children as he can.
This flash-based game consists of six missions where different characters can be controlled. The missions require the player to fend off thugs, lead the children to the port of Genua, free captured children and provide food. The game is entirely controlled by the mouse and shown from a third-person perspective. The left button is used to walk and the right one triggers actions, while the middle button can rotate the camera when held down.
Some educational elements are also present during the introduction of missions, in the book of Thaddeus. Historical characters have a biography, the location of cities is pointed out on a map, historical facts are thrown in, and the use of certain plants is explained.