The player HUD, or Heads Up Display shows all vital information about the player. This includeds things like health and ammo.
The HUD for Chasm: The Rift contains several vital, and not so vital, displays. Firstly, starting from the left, the HUD displays the face of the Marine. The Marines face is usually never seen except for here and in Death Match levels. After that,a number representing the players health is shown. This ranges from 100, full health, to zero, or no health. If a player receives zero health, the player is dead. Next, a box is shown, displaying the type of ammo that the current weapon is using. The picture changes when weapons change. Next to that, is the current amount of ammunition readily available for the current weapon. The only weapon which does not have an ammo display is the Rifle, as it has unlimited ammunition.
Finally, a picture of an armor suit is shown, and next to that, the current amount of armor the player is wearing. This number ranges from 100 to zero. Zero means the player has no armor, and thus no protection from enemy attacks.
Along with the standard HUD, a smaller cut down HUD also exists. It looks like a date (*/*/*) and contains all need to know vitals, including (in this order) Health, Ammo, and armor.