With Half-Life 3 confirmed on a heavily upgraded Source 3 engine, now is the right time to look back at how Valve's engine technology evolved. The story of Source is the story of Valve itself: iterative, pragmatic, and occasionally revolutionary.
Source 1: The Gold Standard
When Half-Life 2 launched in 2004, the Source engine was a revelation. Physics-based puzzles, facial animation that conveyed real emotion, and a modding community that produced games like Counter-Strike: Source and Garry's Mod. Source powered Valve's output for over a decade.
Source 2 and the Live Service Era
Source 2 arrived quietly, debuting with Dota 2's Reborn update in 2015. It brought improved lighting, physically based rendering, and the ambitious but short-lived Steam Machines initiative. Half-Life: Alyx showed what Source 2 could do in VR.
Source 3: Full Ray Tracing
Source 3 represents Valve's biggest engine investment since the original. Full ray tracing, world streaming technology, and a new physics system that promises to make Half-Life 3's set pieces more interactive than anything the studio has attempted before.