Minecraft's "19w04a" Java snapshot update, which rolled out on Thursday, enabled wall running... but not intentionally.
While the Java snapshot update added a handful of things like stone cutting and fixing unlit campfires so they no longer burn you, nowhere does it mention wallrunning, leaving players to surmise that it must have been an unintended side effect of the recent changes. Click here to take a look yourself (thanks, Kotaku).
"Just for context, this isn't a trick or a prank or anything," reported Minecrafter NatalieZem, who shared a brief video of wallrunning on Reddit. "In the recent snapshot, you can't jump while pressing against a block. And apparently not being able to raise your elevation also means you can't lower it either. Try it for yourself: All you need to do is stay sprinting into the wall and you can move along it. Here's another video showing how easy this is to replicate."
The bug's seemingly been resolved now thanks to the arrival of snapshot 19w04b, much to many players' disappointment. "This would be a cool feature though," Redditer JamesBeYeezy opined, while owlindenial had hoped "it's not reported. Ever." "Would be pretty cool if implemented properly," daydreamed Everscream.
The people have spoken, Mojang...