Making video games is a lot of work. With everything from level design to QA testing, there is so much happening at once that must come together for a product to ship in a playable state. Game developers are very resourceful people, and a recent Twitter thread has developers sharing some of their favorite tricks behind the games they make. They highlight the creative problem-solving that comes with the job. Here are some of the best stories in the thread, including a shocking amount about the prevalence of invisible creatures in your favorite games.

Out of sight, out of mind — The tweet that started this all recounted a story from developer Arthur Bruno about the development of Titan Quest. The team ran into a problem where there was no way to delay a quest action once it was triggered. One QA tester discovered a solution: “He ended up using these squirrels we had as ambient creatures as the animation timer, and they became the default timing mechanism.” To make this makeshift clock system a little less conspicuous, all the squirrels were made invisible.

This story began making the rounds on Twitter and other developers started to pitch in with their stories. “The occasional threads of devs sharing extremely hacky fixes and methods that made their games work are easily my favorite things that come out of game dev Twitter by a mile,” one Twitter user wrote.

One thing became clear immediately: Invisible creatures are a universal constant.

“Exploding barrels [in Star Wars: The Old Republic] are filled with shrunken invisible people as only people are a valid damage source,” shared Ubisoft producer Pelle Hoffstein. To make it worse, these people were initially complex models that would tank the frame rate of the game. Some solutions cause more problems.

One Dark Souls modder revealed that “when you interact with a bonfire, you’re actually talking to an invisible character who is standing in the middle of the bonfire.” This system has proved so effective for FromSoftware that this is still the way Sites of Grace work in Elden Ring.

But no talk of invisible animals and game dev would be complete without the infamous bunnies of World of Warcraft. Many people mentioned the horde of invisible bunnies that hold the game together. They are used for everything from casting spells to making quests work. There is a list of every bunny in the game and those not categorized as “critters” are invisible bunnies pulling the strings from behind the curtain.

Smoke, mirrors, and duct tape — While invisible creatures are an industry favorite, there was no shortage of other creative solutions. Josh Sawyer, director of the upcoming Obsidian game Pentiment, shared a tidbit about Fallout: New Vegas: “The ending slides were done in an actual game level with the 1st person camera locked.” In other words, the player is just watching a slideshow in a room like they are stuck in a boring class.

Obsidian loves closed rooms and slides. Technical designer Taylor Swope added a note about a far more recent game: “In The Outer Worlds, any time a character shows up on a monitor, that footage is being captured live in a little diorama just outside the level, with wallpaper made to look like wherever the character is broadcasting from.”

While most of these are creative solutions to problems, some developers reached the point where the best option was to just hide the problem altogether.

This was the case with Settlers III, which had massive desync issues with online matches during development. “The coders spent weeks trying to find the bug,” localization expert Rolf Klischewski revealed. “One day, the error was gone, no error message. The coders were praised by the CEO. Few of us knew that one of them had just REMmed the error message.” In other words, a member of the team made it so the error message would not show up even though the problem remained. This is the state in which the game shipped.

My personal favorite story comes from the original Assassin’s Creed. Horses in the game were “just a fucked up human skeleton,” shared developer Charles Randall. “Cheers to the amazing animators and riggers that managed to make that guy look like a horse!”

At the end of the day, it is a miracle that any game ships in a playable state. But because of the bonkers solutions that devs come up with, we get those experiences and a good story out of it. As the tweet that started this thread puts it:

“Yup, that’s game dev.”