game_zone_player
game_zone_player is a point entity available in all 
GoldSrc games. This entity is used to count the number of players, dead or alive, within the volume of the brush.
Key Values
Targetname:
- Name
(targetname)<string> - The targetname that other entities refer to this entity by.
- Target for IN players
(intarget)<targetname> - All players inside the area covered by the brush fire this target.
- Target for OUT players
(outtarget)<targetname> - All players outside the area covered by the brush fire this target.
- Counter for IN players
(incount)<targetname> - This game_counter's value will be set to the number of players inside the area.
- Target for OUT players
(outcount)<targetname> - This game_counter's value will be set to the number of players outside the area.
- Master
(master)<targetname> - Name of a master entity. (only in
Day of Defeat)
