It's really simple!

[ Madoka smiles, apparently glad she figured out some game he hasn't played before yet so it might not get boring to him as quickly.. ]

You see that piece of rope over there, right..? You're supposed to have a person tugging on both ends of it and then draw a line in the middle between those two people.. and the one who manages to tug the other over the line first wins. It's even more fun with more people..!