Half-Life 2 testers horsing around with physics props 'to make the 47th playthrough of the game more interesting' probably had no idea it would result in Gabe Newell launching a garden gnome into space 16 years later

pcgamer.com:

"Little Rocket Man" is truly one of the greatest bits in videogame history⁠—a challenging achievement in Half-Life 2: Episode 2 that requires you to carry a cherubic little garden gnome named «Gnome Chompski» through the entirety of the campaign and deposit the wee fellow on a rocket ship to another dimension in the final level. The Chompski achievement returned in several later Valve games, including Half-Life: Alyx. It reached apotheosis with Gabe Newell's 2020 IRL recreation, with a tangible Chompski launched into space as a fundraiser for a pediatric charity. And it all began with bored Valve QA testers messing around with physics props in Half-Life 2.

«This small baby doll has a long legacy,» explained Valve developer Scott Dalton in Half-Life 2's new commentary mode while Gordon explores the playground in the game's opening. The baby in question is a scrungly little doll missing an eye and an arm. When you pick the baby up, it makes a little cooing noise, and that's about it⁠—or it would have been if mid-development madness hadn't set in.

«During the long months of internal testing, some of the team turned it into a challenge⁠—a way to make the 47th playthrough of the game a bit more fun,» said Dalton. «They'd place the doll inside a nearby blue crate and see how far they could carry it throughout the game. After Half-Life 2 launched, the community started carrying cratebaby as well, adding their own stories and rules to the mix.

»A few years later, while working on Episode 2, this was the inspiration for the 'Little Rocket Man' achievement, where players had to carry a garden gnome dubbed 'Gnome Chompski' throughout the entire episode. Chompski even made a comeback for Left 4 Dead 2, in the 'Guardin Gnome' achievement, where players had to carry him through the Dark Carnival campaign."

There's been some discussion of the cratebaby over the years, but this seems to be the first definitive accounting from Valve. Some scuttlebut had credited cratebaby as a pure