A player’s health starts at a full 100 percent (or hit points). It may increase even beyond that from the effects of various powerups to as high as 200 percent (199 in versions prior to 1.2). It is decreased by environmental hazards (damaging floors, exploding barrels, and crushing ceilings), and successful enemy attacks. If a player's health ever drops to zero, that player dies.
If a player that has armor is attacked, the armor will absorb some of the damage (one third or one half, depending on the type of armor) and thus lessen the decrease in health.
If a level ends while the player is dead, play proceeds to the next level, but with the player's status reset to that of a newly launched game (100 percent health, no armor, the pistol and 50 bullets).
- The item "health", when given through the "give" command, will give the player 100% health, regardless of the situation. This, however, does not revive a killed player.