  We study monotone P1 finite element methods on unstructured meshes for fully
non-linear, degenerately parabolic Isaacs equations with isotropic diffusions
arising from stochastic game theory and optimal control and show uniform
convergence to the viscosity solution. Elliptic projections are used to manage
singular behaviour at the boundary and to treat a violation of the consistency
conditions from the framework by Barles and Souganidis by the numerical
operators. Boundary conditions may be imposed in the viscosity or in the strong
sense, or in a combination thereof. The presented monotone numerical method has
well-posed finite dimensional systems, which can be solved efficiently with
Howard's method.
