Valve added an invisible wall to its Half-Life 2 tuning, and now it says 'enjoy.'

Valve released a major surprise update to celebrate the 20th anniversary Half-Life 2 (as well an excellent two-hour documentary). It integrated Episodes 1 & 2 with the base-game (so that you can now experience the entire experience seamlessly), and added a new comment track from the old crew. For the coup de grace, every location received a glow-up.

Lovely! You might not notice if you are a Half-Life 2 Speedrunner, one of the freewheeling souls that have long since stopped seeing the G-Man, and instead look at City 17 as the Matrix. They pinball the Freeman between checkpoints on Valve’s hidden flippers. Valve's designers have added an invisible wall in a large sewer pipe when they improved the game. Speedrunners immediately started slamming into it.

The map is Route Kanal, or "d1_canals_03", and it features a puzzle that requires the player to turn a pipe and flood it in order to get through. The upper section of pipe is supposed have an invisible wall that prevents the player from getting through until they've solved a puzzle. However, this was only ever present in the Xbox 360 versions of the game. Therefore, taking advantage of this missing wall by glitching the surface with physics items rather than adding water is a common part of PC speedruns.

The Sourceruns Wiki keeps detailed notes about the differences between the various versions of Half-Life 2; it now has a special section dedicated to the 20th Anniversary Update with various grumbles. It notes that the pipe near the level's end has been blocked by an invisible brush, which was only present in the Xbox 360 versions of the game. The brush will disappear once the player has solved the puzzle the right way.

What good is that for a speedrunner, then? Someone at Valve must have noticed the disquiet, because a few days after, an update for Half-Life 2 reversed this fix, with a direct reference to the reason: "Removed the collision from an underground tube that speed runners love."

The strangest thing is that Valve originally fixed the problem. Valve made a mistake by not including this invisible wall in the PC version. It was obvious that the 360 version had it, and that the PC version should have the same. But I suppose that the unintended consequences were deemed to be worthwhile in their own right.

The anniversary update has broken many speedrunning strategies. Rocket scientists who are experts in "d1_canals_11" should be pity because "the skybox celling has been moved up substantially, breaking old setups to launch over it." Some maps have invisible walls or altered collision points. At times, speedrunners are a little agitated about it. On "d2_prison_01", "every clip brush on map, except those on ladders, had been removed by mistake."

There are a few consolation prize. "d3_c17_05", where the door that the player was supposed to use to enter the building has been changed into a hole and widened significantly, makes it easier to be fast. The floor texture of the apartments has also been changed from concrete to regular floor tiles. "Makes sense!"

Half-Life 2 has a large community that is divided over the version of the game being used. The versions of Half-Life 2 that were released just over a ten-year-old seem to be the most popular.

"We use older builds most often from 2012-2013 at the top level," said speedrunner "Peng", an HL2 world records holder. "But I do find that it's unfortunate that we are missing out on new changes ..."

Peng says that the "Item Saving Glitch" changes will not make the anniversary build popular with speedrunners. This is because it allows users to skip sections of the game, and save money by glitching through walls. He does admit, albeit with a casual brutality that Valve's fix will make it "viable" for beginners again.

The anniversary update is a treasure trove of Half-Life 2 content. Valve's documentary is both a making-of-the-game and a time capsule from an era when Valve wasn’t yet Valve. No-one believed Steam would work. Testers were going stir-crazy, and playing with gnomes in order to make their 47th playthrough more bearable. And for the first time, we get a real insight into the unshipped Half-Life 2 Episode 3.