Developer(s) Valve Corporation Publisher(s) Valve Corporation Sierra Studios (former) Microsoft Game Studios (Xbox) Distributor(s) Steam (online) Designer(s) Minh "Gooseman" Le Jess Cliffe Engine GoldSrc ( Half-Life ) Version 1.6 (September 9, 2003) [ 1 ] Platform(s) Microsoft Windows , Xbox Release date(s) Windows WW June 19, 1999 (Mod) NA November 8, 2000