Arkane Studios, a game developer known today for the excellent Dishonered and Prey games, worked with Valve in 2006-2007 to develop a spin-off game for Half-Life 2 titled Return to Ravenholm. Unfortunately, like so many other Valve projects, the game eventually ended up in a junkyard and Arkane Studios moved on to other projects. Now, however, the Noclip channel, which makes crowdfunded game documentaries, has made the game studio an excellent documentary, The Untold History of Arkane, in which several people who worked on Ravenholm are heard and a long clip of its alpha version is seen.
Based on the documentary, Return to Ravenholm would have been a very interesting game as it would have continued the story of Adrian Shepard, the protagonist of the original Half-Life Opposing Force add-on. In the game, the player would have used a magnetic gun instead of a gravity weapon, which would have acted not only as a weapon but also, of course, as an aid in solving puzzles.
The documentary, which explores the entire history of the game studio as well as other canceled projects, is definitely worth watching as a whole, but if you directly want to see what the Ravenholm game would have looked like, you might want to jump around 33 minutes in the video below.
https://www.youtube.com/watch?v=h4kdqwdbZZ8
