Twenty years ago this month, Valve released Half-Life 2. The company is celebrating the anniversary with a 20th anniversary update that includes new content and various bug fixes. Best of all, Half-Life 2 is free right now on Steam, but only until 1 PM ET today, November 18.

One of the most exciting additions for the Half-Life 2 update is new commentary tracks (spanning 3.5 hours) for the entire game featuring the original Half-Life 2 developers discussing how they brought the game to life. Additionally, Half-Life 2 now has in-game Steam Workshop support, along with support for Steam’s new Game Recording feature. The update also fixes various issues with the 20-year-old game, including holes in the game world and disappearing objects. Players can also expect “cleaner, smoother horizon lines” and higher-resolution lightmaps across the entire game.

What’s more, players can choose original graphics settings for blood and fire effects or new ones that were released later. There is also a High Quality mode that’s been added, while the aim assist feature has ben overhauled to help it feel better.

Something else to know is that Half-Life 2’s Episodes 1 and 2 are now part of Half-Life 2 itself, and due to this, Valve said it will be “reducing the visibility” of the standalone versions on Steam. They will now appear inside the Tools menu on Steam.

In addition to the update, Valve partnered with former GameSpot video producer Danny O’Dwyer’s Secret Tape for a two-hour documentary about Half-Life 2. In this feature, Valve discusses the game’s origins, development, and legacy, and of course, the fabled Half-Life 2: Episode 3. Kotaku reports that in the documentary, Valve discussed why Episode 3 never saw the light of day and even revealed new footage of the game. Episode 3 would have been set in the Arctic and would have focused on a ship, Borealis, that went missing.

The game was in the works for six months, but amounted to a “collection of playable levels in no particular order” and only containing some story elements. However, writer Marc Laidlaw said the team was “running out of fuel” and ultimately decided to abandon Episode 3 altogether as the team worked on finishing Left 4 Dead, which would be released in 2008 to great success.