How to play the secret MS-DOS game from your childhood

From 1991, every copy of MS-DOS (and many versions of Windows) featured 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 you can play it today.

The simple magic of gorillas

It’s 1992 and you’re sitting in your school’s computer lab. In between assignments, whisper to your friend, “Look at this.” In the C:\DOS folder, run QBASIC.EXE and then load GORILLA.BAS. Before long, you and a friend are two gorillas pitted against each other atop skyscrapers with exploding bananas.

If you grew up with a compatible IBM PC in the early 1990s, chances are you’ve seen or played Gorillas, a free QBasic game was first included with MS-DOS 5.0 in 1991. It was distributed by hundreds of millions, if not billions of PCs in the 1990s.

Gorillas builds on 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 force. You also need to consider the wind speed, which can blow your explosive banana off course.

The Gorillas title screen.

If you tilt your launch just right and hit the other gorilla with your banana, it will explode and slap your gorilla on the chest to celebrate. 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), fun sound effects, and simple two-player gameplay, Gorillas has 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 to be.

RELATED: PCs Before Windows: What Using MS-DOS Was Like?

Stopping new games in MS-DOS

MS-DOS, the command line operating system, debuted as PC DOS with IBM PC in 1981. Until the release of MS-DOS 5.0, Microsoft had never marketed its DOS operating system as a standalone retail product. “Basically, the MS-DOS team had previously only shipped to OEMs and never in retail,” recalls Brad Silverberg, then the Microsoft VP responsible for MS-DOS 5.0.

Microsoft had to spice things up a bit because selling copies of MS-DOS at retail wasn’t as secure as selling to OEMs. “We had to build an attractive product and an attractive sales proposition,” says Silverberg. “It was a total change in the way both the product team and the marketing team had to think. It had to be something people wanted to buy, rather than software that they didn’t have much of a choice in that came with their new computer.”


With this in mind, Microsoft began adding notable features to MS-DOS 5.0 prior to launch, including an uninstall utility, a graphical 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 BASEso Microsoft decided to record four sample 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 has transferred existing BASIC source code — sourced from sources outside the company — for a artillery game and a snake game to a group of computer science college students from their “co-op” internship program. Their goal was to rewrite the code in new games that Microsoft could legally publish with MS-DOS.

Rick Raddatz, who programmed Nibbles, remembers the origin of the games somewhat differently: “Nibbles was a game I wrote myself for the TRS-80 in 1981, based on a game called Rush. Seven years later, they asked if anyone had any ideas for BASIC games, I suggested 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.”

Nibbles, the other QBasic game that came with MS-DOS 5.

Three co-op workers volunteered to rebuild the artillery game that became Gorillas: Moe, Lance Delarme, and Lyle Hazle. According to Moe, he did the design, wrote the music and sound effects, created the art (including the gorillas themselves), and some display logic. Delarme programmed the core mechanics of the game and Hazle concentrated on the code for generating cityscapes.

As for the origin of the gorilla theme, Moe said Microsoft had to stay away from artillery tank battles for legal reasons: “I specifically remember brainstorming crazy ideas. One idea was that clowns were throwing pies, but what do clowns do on buildings? King Kong on the other hand…”

The trio of developers worked on Gorillas for a few months in 1990 as a side project to their regular duties at Microsoft. launched with MS-DOS 5.0 in June 1991. DOS 5 was a huge success for Microsoft, leading to: good reviews, which caused gorillas to spread rapidly around the world. “We succeeded far beyond our expectations,” recalls Silverberg of the success of MS-DOS 5, “and it gave us momentum for Windows 3.1 and Windows 95.”

RELATED: Windows 95 Turns 25: When Windows Got Mainstream

The Legacy of Gorillas

One of the most compelling features of Gorillas is that the source code was fully viewable and editable, which: invited experimentsespecially for children 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 everything else in the game.

From scanning Twitter and blogs, more than a few programmers owe their fascination for developing or programming computer games to Gorillas.

Funnily enough, many adults didn’t even know Gorillas were there, leading to episodes of secret gaming in computer labs around the world. A youtube comment by Allen Puckett recalls, “I remember in high school 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 had the computer hacked or brought in, then everyone started playing it, and it got so bad you’d be banned.”

I remember similar scenes in my school’s computer labs, with kids circulating how to launch Gorillas as if it were some 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 up to Windows 2000. Raddatz recalls how the QBasic games came to an end: “It wasn’t until I gave the NT team a new version of Nibbles gave that increased hardware speed which they said, ‘Wait, is that still there?’ And then they took out the games!”

As for Moe, Gorillas certainly had an impact on his life trajectory. After transitioning from computer science to liberal arts in college and earning a degree, he sought a job that matched his programming experience.

Richard Moe, co-creator of Gorillas, later worked for Humongous Entertainment, which created the popular games Pajama Sam and Putt-Putt. Richard Moe

“I have interviewed for, of all things, a computer game company called Gigantic entertainment‘ says Mo. “When they found out I coded Gorillas, they actually gave me the job. And then I went on to make 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 with people of a certain age and I get a lot of stories about how it fueled their love of programming! Pretty cool,” says Moe, who now works at Apple. “Twenty-one years in the game industry for me and then on to other roles in technology at Amazon and now Apple, thanks to that game.”

How do you play Gorillas today?

Today, the easiest way to play an authentic Gorilla game is 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 also in a similar way.)

When you load the page, press the “power button” in the center of the box on the screen to start the virtual computer. It loads QBasic from MS-DOS and you see the code for Gorillas in a blue box on your screen. To play the game, click on the emulator box and press Shift+F5 on your keyboard.

After pressing a key in 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 and the degree of gravity. Then press “P” to start the game.

People have also recreated Gorillas in other programming languages, such as: Python, Fastand javascript, among other things. Not bad for a modest sample program released nearly 31 years ago. Have fun!

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