You don't lose the game for having 0 or less life.
As long as you have 0 or less life, all damage is dealt to you as though its source had infect. (Damage is dealt to you in the form of poison counters.)
"While the realm's great minds quarreled over the strange eclipse, Locthwain fell to the invaders."
—*Last Stand of the Realm*
Artist(s): Harry Conway