The following are the values at which the color of the counter changes. For example, if hud_armor_green is 100, the armor counter is green at 100 and below.
hud_armor_green=int hud_armor_yellow=int hud_armor_red=int hud_health_green=int hud_health_yellow=int hud_health_red=int hud_ammo_yellow=int hud_ammo_red=int
hud_showitems=bool (items picked up compared to total count) hud_showmonsters=bool (monsters killed compared to total count) hud_showscore=bool (score earned so far) hud_showsecrets=bool (secrets found compared to total count) hud_showstats=bool (stamina and accuracy, usually only relevant for Strife)
The following determines if the alternate HUD is used at all.
The following determines the scale at which the alternate HUD elements are drawn.
The ALTHUDCF lump in a mod allows to configure the alternative HUD, notably to determine the icons used by weapons and ammunition.