There’s a whole phase to the game of Marathon that occurs right when you might assume it’s over. It begins with the jolting sound effect that indicates a teammate has been downed – knocked on their back by volt fire or a claymore in a dark corner. Then, as you rush to help, a second jolt: another teammate pummeled into helplessness by an unseen assailant. Footsteps all around: a full enemy team, and you alone, as the revive timers of…