  We prove that finding an $\epsilon$-approximate Nash equilibrium is
PPAD-complete for constant $\epsilon$ and a particularly simple class of games:
polymatrix, degree 3 graphical games, in which each player has only two
actions.
  As corollaries, we also prove similar inapproximability results for Bayesian
Nash equilibrium in a two-player incomplete information game with a constant
number of actions, for relative $\epsilon$-Well Supported Nash Equilibrium in a
two-player game, for market equilibrium in a non-monotone market, for the
generalized circuit problem defined by Chen, Deng, and Teng [CDT'09], and for
approximate competitive equilibrium from equal incomes with indivisible goods.
