Bugs as Features in Video Games

A brief history of happy accidents that became celebrated by fans

Published in
6 min readFeb 4, 2021


For all of the mechanics game developers painstakingly build into their games, there are a not-so-insignificant number that were originally glitches. Is it a bug or a feature? Why not both?

They don’t need to be removed

Some bugs are game-breaking, ruining the enjoyment of the medium and must be removed. Others are worse still, crashing a game, making it literally unplayable. There are those bugs, though, that don’t need to be addressed.

For instance, Stardew Valley’s bachelorette NPC Abigail seems to have been made with a bit of an oversight in her dialogue. When gifted an item she likes, she says, “Hey, how’d you know I was hungry? This looks delicious!”

This is not worth raising an eyebrow most of the time. Her likes are almost all crops or foods you can grow or forage for in the game. In that context it makes perfect sense. However, the mineral quartz is listed among her likes. The same dialogue triggers and has many players wondering if she…eats quartz?

By the way, quartz is harder than iron.

A harmless oversight in dialogue that doesn’t need to be removed. After so many updates to the game we can only conclude that it has been left in exactly because it is harmless.

Even better yet the developer Concerned Ape seems to have leaned into this. After marriage Abigail, as your spouse, can comment that if you’re heading to the mines (where quartz is most often found) to bring her back something tasty. I can’t stress enough how much I enjoy knowing a game’s developer has a sense of humor.

They can actually make the game better

A famous example of a game improved by an unintended behavior would be found way back with Space Invaders — yeah, that Space Invaders.

For those that have not had the pleasure of experiencing the retro game so many others are based on, Space Invaders is a simple arcade shooter. Baddies move down the screen in a predictable fashion as you blast them from below (hopefully) before they reach you. Said invaders move slowly at first, and pick up the pace as you clear some out. The better you do, the harder it gets.

I cannot think of a more iconic image for “video game enemy” than a space invader.

That was, however, an oversight. The number of enemies on the screen determined how fast the game ran on hardware at that time. Removing enemies by shooting them made the game faster because there were fewer to draw on the screen. It was by all accounts, a happy accident.

Another example from the dawning of video games is the classic Super Mario Bros. coin block. You know how you can hit them multiple times to get extra coins out? Yeah that, too, was unintentional.

More than a decade later Starsiege: Tribes would stumble into its signature game mechanic. This mechanic involved jetpacking up hills, and frictionless-sliding down them, which when combined just right could enable players to traverse level geometry lightning fast. Since then A number of other Tribes games have been released, as recently as 2012, and still feature this movement tech.

How many of our favorite games, old and new alike, have mechanics that worked well purely by accident? In the end, a good mechanic is a good mechanic, even if it wasn’t the brainchild of some ingenious developer.

They occasionally make the game

Portions of games being born from coding errors is one thing. It’s entirely possible to trip and fall into success, even when it comes to video game mechanics. A whole game, though? Yes whole games can crop up because of bugs.

Grand Theft Auto, for all of its successes, started out because of a bug. What was supposed to be a racing game had police AI that were too aggressive, and from that glitch we eventually had the chaotic environment you’ll find online with GTA 5.

Goat Simulator is arguably more bug than feature. But that’s what made it so famous. Source: Kotaku.

The developers of Goat Simulator purposefully left every physics bug in that didn’t crash the game because they thought it was hilarious. They were right. Not all games have to take themselves seriously, and an environment of ridiculousness can allow bugs to thrive in a positive light. The idea of keeping in bugs for their humor or value wasn’t new. What was new, however, was having this idea at the very core of the game. Goat Simulator without broken physics just wouldn’t be the same, and I dare say it would make it drastically worse.

Embrace the bugs

If any of the previous examples of bugs, glitches, or unintended game behaviors have shown anything I hope it’s that bugs are not to be feared. A good engineering mindset can lead to squishing every bug the moment it crops up. Most of the time that’s exactly what you should do, of course. Maybe just keep an eye out for those that might subtly be adding rather than subtracting from the game as a whole.

A bug that isn’t devastating may not even seem like it’s a bug to a particular player. If you’re commended on a fun gameplay mechanic, only to find out you did some math incorrectly, don’t immediately fix it. Give it a shot, see how other players and groups respond to it.

Bugs can teach us

The creation of bugs and their evaluation of features can itself serve as a great educator. A mechanic may seem well tuned until player feedback or other data tells another story, and in that way the very nature of game development teaches us how to be better at it.

There are other teachable moments. One of the most infamous bugs in one of the largest video games to date would end up studied by epidemiologists. World of Warcraft had a bug that brought what is now called the Corrupted Blood incident.

Countless players fell to this digital pandemic.

A glitch that allowed a high-level affliction called Corrupted Blood to be spread outside of its intended quarantine zone would wreak havoc on the WoW ecosystem. What was a nuisance to high-level players was utterly devastating to lower-level players if they caught it. Player behavior once this affliction took hold of the general populous was of particular interest to epidemiologists who looked at how it might mirror real-world behavior.

It happened long enough ago that there are a multitude of in-depth articles on the internet (not to mention wikipedia) that do a great job of explaining its intricacies. If this kind of thing interests you I’d strongly suggest you going to take a look because the whole event is truly fascinating.

Though bugs can be seen as something just to be squished this and countless other examples tell us they can be invaluable. Don’t be afraid to add new features in a hurry. Those mechanics, buggy at first, may shine a light on some untapped part of your game you’ve yet to see. It may come back to bite you, but it could also be your saving grace.




Software developer by day, gamer by night. I use medium to write about video games and some of their many aspects.