Add an exploration reward

def reward_explore(self):
        """
        Add an exploration reward
        """
        if not 'explore' in self.mode:
            return
        mode = self.mode['explore']
        if mode and mode['reward'] and self.__test_cond(mode):
            self.player.stats['reward'] += mode['reward']
            self.player.stats['score'] += mode['reward']

            self.player.game_over = self.player.game_over or mode['terminal']