The tension is KILLING me!

Any worthwhile story has a source of tension that propels the characters, and usually a central protagonist who must confront the problem and overcome obstacles en route to a discovery of self or other. Endgame is a classic drama – but one which avoids some of the trappings and traditions of pre-twentieth-century literature. What is the tension at play in this work? Who is the “hero” and what is his journey and discovery?