The obstacle problem for the $p$-laplacian via optimal stopping of   Tug-of-War games
  We present a probabilistic approach to the obstacle problem for for the $p$-Laplace operator. The solutions are approximated by running processes determined by tug-of-war games plus noise, and letting the step size go to zero, not unlike the case when Brownian motion is approximated by random walks. Rather than stopping the process when the boundary is reached, the value function is obtained by maximizing over all possible stopping times that are smaller than the exit time of the domain. 
Marta Lewicka and Juan J. Manfredi
math.AP math.PR