Last week, 12TB of Valve's internal game assets leaked online. Not screenshots or trailers. Not design documents. The actual 3D models, textures, and level geometry from over a decade of cancelled projects, abandoned sequels, and content that never saw the light of day. We're talking pre-release builds of Portal 2 and Half-Life 2: Episode 3, playable prototypes that existed only in PowerPoint presentations, and entire games that were shuttered before anyone outside Valve knew they were in development. The leak spans both Valve's first-party projects and third-party games published through Steam, which means we're not just looking at what Valve chose to cancel. We're looking at what publishers and developers were willing to throw away when a project didn't pan out. Some of this stuff is fascinating — weapon designs that evolved dramatically from early concepts, character models that hint at story directions that were completely scrapped, gameplay mechanics tha...