Shoot the three headcrabs and get the message.
N.B. - the game_text has the "All Players" flag checked; the headcrabs have trigger_condition="Death" and trigger_target="death_counter"
Uses: game_counter game_text entities, trigger_condition and trigger_target attributes of monster_headcrab
I'll try to learn it from your map.
But on the computer i'm using now hasn't got half-life! OMG!
I'll try to not panic..
/.Madcow