For the friend, life's a trip. But it's just that most people are tripping really hard.
For the old boy, shrugging a playful shrug, life is just a game. Albeit a noble one. Whatever life is, the man continues to walk his walk, with one foot in fear and the other in wonder of it all.
Sisyphus is an existential tale - an allegorical, Dante-esque and surreal walking meditation through a not too distant future. Questioning the notion of Will and Choice against Nature and inevitability, it is ultimately an homage to life and to living.