In Factories the object is to collect at least one of each of the ten resources. This is done by creating factories with the cards drawn. A factory consists of one output card, and any number of equation cards. By paying the costs in the equation cards, in order, you produce whatever the output card indicates. This alone would be a little like solitaire, so enter the challenge you can make once per turn. Challenge anyone for up to three resources, and then each bid a secret amount more. Whoever has more wins everything, unless they overbid by more than three in which case the lower bid wins! This allows for player interaction, although not a high degree of such.