Be careful how you say that. It's Half-Life "free", not Half-Life "three". If you say that one wrong, people will get very upset.
It’s not Half-Life 3, but Half-Life: Alyx may be the closest we ever get.
This is a work of fiction. Any resemblance to actual persons, living or dead, or anything that might be copyright Valve Corporation, is purely coincidental.
A fan-made Half-Life 2 sequel to Opposing Force, bringing back Adrian Shephard to assist Gordon Freeman during the assault on Nova Prospekt? Yes please!
Why not reacquaint yourself with Half-Life and Half-Life 2 while you wait? Some community-created mods might just surprise you...