Whether or not it is to Gawain's advantage to play the Green Knight's game is not really the reason he steps up; actually, he plays the game so Arthur won't die because of some playful but deadly stunt. When the Green Knight challenges the Knights of the Round Table, no knight stepped up, so Arthur did in order to save the kingdom from embarrassment. Gawain plainly says to Arthur, "For I think it not seemly when such challenges be made in your hall that ye yourself should undertake it"(5) because he understands the embarrassment that the king might feel if anything horrible should happen. At the time that the Green Knight presents himself to the court, too, no one could have guessed that he was going to pick up his own head and walk out of the dining hall. Had Gawain known beforehand that the Green Knight was so tricky, he still would have stepped up to take the challenge because that is the type of man and knight he is-- one who would gladly die for his lord than have him suffer any embarrassment or dishonor.