Half-Life 2 Episode 4: Return To Ravenholm was a game in the series of Half Life 2 episodes being developed in 2006 and 2007 by Valve Software and Arkane Studios. It was presumably canceled because Valve never finished Half Life 2 Episode 3. Only a few screen shots exist of the game, as it was presumably canceled. The protagonist might not of been Gordon Freeman, according to Valve News Network.
According to a 2006 PC Gamer article, the game was to fall outside of the first 3 Half Life 2 episodes' story archs, instead following a story of it's own. The screen shots show new weapons, a blue HEV suit, and an Absorption meter. The Absorption meter could indicate a radiation system, similar to games like Fallout 3.