Half-Life 3

Half-Life 3 was in development as a full-fledged sequel to Half-Life 2 following the cancelation of Half-Life 2: Episode Three and the transition to the Source 2 engine. It was in development by a small team headed by David Speyrer from 2013-2014, and would have been a singleplayer shooter which combined handcrafted levels with procedural generation to create a more replayable experience.

An example of the gameplay given by Speyrer was that the game could "find a building, seal up all the windows so there was only one way in, put a citizen or prisoner somewhere in the building, and then populate the building with enemies", with the player having to find a way into the building and to the prisoner through a route that was different every time. The game was also set to feature the return of the G-Man, with a new scan being taken of his original face model Frank Sheldon.

The game was canceled in 2014 because the Source 2 engine was not yet suited at that time to support full-scale development.