Starting in 1991, every copy of MS-DOS (and many versions of Windows) included a hidden artillery game called Gorillas. It inspired a generation of programmers and drew the ire of computer lab instructors everywhere. Here’s how it came to be—and how to play it today.
The Simple Magic of Gorillas
It’s 1992, and you’re sitting in your school’s computer lab. In between assignments, you whisper to your friend, “Check this out.” In the C:\DOS directory, you run QBASIC.EXE, then load up GORILLA.BAS. Before long, you and a friend are two gorillas battling it out atop skyscrapers with exploding bananas.
If you grew up with an IBM PC compatible during the early-mid 1990s, chances are high that you’ve either seen or played Gorillas, a free QBasic game first included with MS-DOS 5.0 in 1991. It was distributed with hundreds of millions, if not billions, of PCs in the 1990s.
Gorillas builds off a long, proud lineage of artillery games on computers and game consoles. To play, you enter two variables: the angle of your banana and the power. You also have to take wind speed into account, which could blow your explosive banana off course.
If you angle your launch just right and hit the other gorilla with your banana, it explodes, and your gorilla beats its chest in celebration. People who have played Scorched Earth or Worms will immediately be familiar with the basic mechanics of the Gorillas.
With charming graphics (including CGA and EGA support), amusing sound effects, and simple two-player gameplay, Gorillas crammed a lot of timeless gameplay into just 1,134 lines of code. Until now, no one has ever explored how this legendary game came about.
Tucking New Games into MS-DOS
MS-DOS, the command-line operating system, debuted as PC-DOS with IBM PC in 1981. Up until the release of MS-DOS 5.0, Microsoft had never marketed its DOS operating system as a standalone showcase retail product. “Basically, the MS-DOS team previously had only shipped to OEMs and never retail,” recalls Brad Silverberg, then the Microsoft VP in charge of MS-DOS 5.0.
Microsoft needed to spice things up because selling retail copies of MS-DOS individually wasn’t as much of a sure bet as selling to OEMs. “We had to build a compelling product and a compelling selling proposition,” Silverberg says. “It was a total change in the way both the product team and marketing team had to think. It had to be something people wanted to buy, rather than some software they didn’t have much choice about that was included with their new computer.”
With this in mind, Microsoft began adding notable features to MS-DOS 5.0 before launch, including an undelete utility, a graphic shell (DOS Shell), a full-screen text editor (MS-DOS Editor), and a new BASIC interpreter called QBasic.
QBasic’s syntax differed dramatically compared to its predecessor, GW-BASIC, so Microsoft decided to include four example programs to help new programmers get started with the language. These programs came with file names such as MONEY.BAS (a personal finance manager), REMLINE.BAS (removes line numbers in a program), NIBBLES.BAS (a snake game), and of course, GORILLA.BAS.
According to Richard Moe, one of the creators of Gorillas, Microsoft handed off existing BASIC source code—pulled from sources outside the company—for an artillery game and a snake game to a group of computer science university students from their “co-op” intern program. Their goal was to rewrite the code into new games that Microsoft could legally publish with MS-DOS.
Rick Raddatz, who programmed Nibbles, recalls the games’ origins somewhat differently: “Nibbles was a game I wrote myself for the TRS-80 in 1981 based on a game called Hustle. 7 years later, they ask if anyone has any ideas for BASIC games, I proposed it, and they said yes.” Referring to Gorillas and Nibbles, Raddatz recalls, “We were the two winning ideas in the team-wide call for ideas.”
Three co-op employees volunteered to convert the artillery game that became Gorillas: Moe, Lance Delarme, and Lyle Hazle. According to Moe, he created the design, wrote the music and sound effects, made the art (including the gorillas themselves), and some display logic. Hazle programmed the core mechanics of the game, and Delarme focused on the cityscape generation code.
Regarding the origins of the gorilla theme, Moe mentioned needing to distance Microsoft from artillery tank battles for legal reasons: “I remember specifically brainstorming silly ideas. One idea was clowns throwing pies, but what are clowns doing on buildings? King Kong on the other hand…”
The trio of developers worked on Gorillas as a side project in addition to their regular duties at Microsoft for a few months during 1990. The game launched with MS-DOS 5.0 in June of 1991. DOS 5 was a huge success for Microsoft, leading to good reviews, which ensured that Gorillas spread quickly around the world. “We succeeded way beyond our expectations,” recalls Silverberg of MS-DOS 5’s success, “and it gave us momentum for Windows 3.1 and Windows 95.”
The Legacy of Gorillas
One of the most compelling features of Gorillas is that its source code was fully visible and editable, which invited experimentation, especially for kids at the time.
Want to change the speed of the game? Set the variable “SPEEDCONST” to a higher value. You could also change whether your own bananas blew you up, the influence of the wind, and literally anything else in the game.
From scanning Twitter and blogs, more than a few programmers owe their fascination with computer game development or programming to Gorillas.
I definitely used earlier versions of DOS but I do have fond memories as a child opening MS-DOS 5 with BASIC so I could “hack” the code for Gorillas 😂 https://t.co/KAkYCRZIgz
— Matt Wicks 💉💉💉 (@matteightyate) October 1, 2021
Amusingly, many adults didn’t know Gorillas was even there, leading to episodes of secret gaming in computer labs around the world. One YouTube comment by Allen Puckett recalls, “I remember in high school back when we were learning DOS and Windows 3.1 all the kids thought this was some kind of hack, and the teacher wasn’t even aware of it and thought we hacked the computer or brought it in, then everyone started playing it, and it got so bad that you would get suspended.”
I remember similar scenes in my school computer labs as well, with kids passing around how to launch Gorillas as if it were a deep secret, usually to the instructor’s surprise.
After its release with MS-DOS in 1991, Gorillas shipped with every version of MS-DOS and Windows until Windows 2000. Raddatz recalls how the QBasic games met their end: “It was only when I gave the NT team a new version of Nibbles that accounted for increased hardware speed that they said, ‘Wait, that’s still in there?’ And then they pulled the games out!”
As for Moe, Gorillas definitely had an impact on his life trajectory. After switching from computer science to liberal arts in college and getting a degree, he looked for a job that played off of his programming experience.
“I interviewed for, of all things, a computer gaming company called Humongous Entertainment,” says Moe. “When they found out I coded Gorillas, they basically gave me the job. And then I went on to create other ‘impactful’ games (in some circles) like the Pajama Sam series and Backyard Sports franchises with Humongous.”
“Over the years, I’ve shared my Gorillas story to people of a certain age and I get a lot of stories about how it kindled their love of coding! Pretty cool,” says Moe, who now works at Apple. “For me, twenty-one years in the games industry then on to other roles in tech at Amazon and now Apple, thanks to that game.”
How to Play Gorillas Today
Today, the easiest way to play an authentic game of Gorillas comes courtesy of the Internet Archive, which lets you run the original GORILLA.BAS file in an MS-DOS emulator in your favorite modern web browser. (You can play Nibbles in a similar way, too.)
When you load the page, press the “power button” in the middle of the box on the screen to start the virtual computer. It will load QBasic from MS-DOS, and you’ll see the code for Gorillas in a blue box on your screen. To play the game, click the emulator box and press Shift+F5 on your keyboard.
After pressing a key at the title screen, you can enter the name of the two players (there is no computer-controlled player), how many points you want to play to, and the rate of gravity. Then press “P” to start the game.
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