ProblemScape: Value of Xperts

ProblemScape takes you to the strange city of Arithma in search of your lost sibling. You need help finding them, but who can help you? The inhabitants of Arithma, the Arithmen, are by nature helpful (that is, when they're not playing paintball). The mayor of Arithma can help too, but you have to find him first, which is not always easy - he goes into hiding at the first sign of trouble! It turns out the Arithmen need your help too. The only ones in Arithma who can do math, the Xperts, have all vanished! Could this be connected to the disappearance of your sibling? And how can a city function without anyone knowing math?