12 Things You Didn't Know About Half-Life 2
8. Episode Four
Whilst they continued their attempts at developing Episode 3, Valve had already begun plans for making Episode 4. Its existence was revealed by Gabe Newell in May 2006, explaining this would be a standalone episode, separate from the episodic trilogy.
Whilst not much became known of Episode Four at the time, further details were revealed back in 2015 that it was under development with Warren Spector’s company, Junction Point Studios. It would've brought in new mechanics, with Spector teasing a "Magnet Gun that would operate differently from the Gravity Gun" and that both "would have been super complementary".
Revealing this chapter would focus on Ravenholm with a focus on Father Grigori, Spector confirmed that Junction Point ended up doing concept development for Valve whilst also working for Disney on a project that became Epic Mickey before it was cancelled. Episode Four's development wasn’t abandoned however and this soon passed to Arkane Studios.