Boulder Dash began as a screen full of random rocks. Peter Liepa, a self-taught Canadian programmer and, in Edge’s words, “a card-carrying maths geek”, had bought an Atari 800 because he thought “I can write a game”. He found that digging through heaps of rock and dirt with a joystick was fun in itself, and built a game around it. Its hero, Rockford, collects jewels in caves where anything unsupported falls, and every tunnel he digs can bring a landslide down on his head. First Star Software published it for the Atari 400 and 800 in 1984. Within months it was in American arcades, on the Commodore 64 and the Spectrum, and at the top of British review pages, and new versions were still coming out forty years later.
Explore the Boulder Dash study for a closer look at digging, falling, cave design and the people who kept making new situations from its rules.
Fast facts
- Designer and programmer: Peter Liepa, from an idea by Chris Gray.
- Publisher: First Star Software, New York, 1984; in Britain, Statesoft (Commodore 64) and Front Runner (Spectrum).
- Original machine: Atari 400/800, on disk, tape or cartridge.
- Structure: 16 caves lettered A to P, four bonus intermissions and five difficulty levels.
- Arcade: Exidy’s Max-A-Flex version in 1984 and Data East’s in 1985.
- Sequels: Boulder Dash II (1985), Boulder Dash 3, the Boulder Dash Construction Kit (1987), and many more, up to Boulder Dash 40th Anniversary (2025).
From a demo to a cellular automaton
Liepa told Retro Gamer in 2006 that after buying his Atari he contacted a local publisher, which introduced him to Chris Gray, who had “submitted a demo written in BASIC”. The demo was unfinished and needed to be rewritten in assembly language to be sold. It played much like the arcade game The Pit, although Gray said he did not know that game, and in it “the action was very hard-coded: rocks followed predetermined sequences, and there wasn’t much for the player to do”. Liepa decided it was not worth converting and went his own way. Gray’s part, in Liepa’s account, largely ended there, although he kept a credit on the finished game.
Instead Liepa wrote the rules. “The game’s original graphics were crude — just squares, circles and spaces — and what evolved was a cellular automaton that encoded the basic physics of what was to become Boulder Dash,” he said: a grid in which every square follows the same few rules, so that complicated behaviour grows out of simple parts. He filled screens with random rock and dirt and dug through them. Then, “I needed some way of keeping score, and so I added jewels. And I had to add risk, so now you died if you were hit by a rock.” Every creature that followed was there, he said, either to make more jewels or to kill Rockford.
He worked slowly, about two hours of coding a day, and finished in about six months, Edge reported in 2010. The magazine also wrote that he built the game in Forth, the stack-based language, while Liepa himself remembered fitting it into “4K — or was it 8K?” of “assembler instructions”. The first publisher he approached dropped out, but not before insisting that the stick man, whom Liepa called just “the man”, “needed to be a recognisable character”. Liepa doubled the size of everything on screen, which meant writing a scrolling routine, and in doing so gave Rockford his big head: “Given the coarse pixels available, his head had to be fairly large just to accommodate his eyes.” He then sent a demo to publishers, and First Star Software took it.
Rocks, jewels and landslides
Each cave is several screens wide, and Rockford must collect a set number of jewels before the time limit runs out; then the exit opens. Personal Computer Games set out the rules for its readers in December 1984:
- Dirt disappears when Rockford digs through it, and no longer holds up what was above it.
- A boulder does not fall while Rockford stands under it, but falls into the space as soon as he moves away.
- A boulder resting on another boulder or on a wall topples off if the space diagonally below it is clear.
- Rockford can push a single boulder sideways if there is space on the other side.
- A falling boulder, or a falling jewel, kills him.
The living things are few. Fireflies patrol the empty spaces and kill Rockford on contact, but explode when a boulder falls on them. Butterflies move the opposite way and are just as deadly, but crushing one turns it into jewels. The amoeba, a green ooze, spreads through the dirt: shut it in with boulders and it turns into jewels, but let it grow too big and it becomes boulders instead. Magic walls turn falling boulders into jewels, for a short time. ANALOG Computing noticed that the game did not simply get faster: harder levels rearranged the caves and raised the number of jewels needed.
Liepa never wrote a cave editor. He wrote “a simple cavern definition language that allowed me to draw points, lines and rectangles consisting of characters, along with specifying random densities”, he told Retro Gamer. The rocks, dirt and jewels in a cave are placed by a random-number generator from a few frequencies, and the walls, fireflies and butterflies are laid over them by hand; “randomisation was used as a lazy way of designing caves”, he said, but the results were as good as hand-made ones. The first cave was an exception. First Star asked for an easy one, and Liepa designed what he called a “granny” cave, “so called because your grandmother could sit down and finish it!”
The small touches were noticed too. Leave Rockford alone and he blinks, folds his arms and taps his foot, a detail the reviewers kept mentioning. Liepa added it so that he would have “autonomy of his own — he’s not just a puppet that you manipulate”. The screen scrolls only when Rockford nears its edge, so the player sees less of what is ahead.
The reviews
ANALOG Computing’s Tom Hudson admitted in July 1984 that the magazine’s staff had “never been very impressed” with First Star’s games, and called Boulder Dash “an exceptional game, and one of the best yet for the Atari computer systems”. It cost $29.95 on disk or tape and $39.95 on cartridge. His one complaint, as a programmer, was that the creatures “jump” from square to square instead of moving smoothly. Electronic Games found the manual thin but thought the game “can’t be mastered in a mere few play sessions”.
In Britain the Commodore 64 version came from Statesoft at £8.95 on cassette and £10.95 on disk, and Personal Computer Games made it Game of the Month in December 1984. “This game is so addictive that if it were sold on the streets angry parents would petition Parliament to have it banned,” wrote Peter Connor. Liepa later said that of all the conversions, “the C64 conversion was by far the most faithful to the original.” Front Runner, the software label of K-Tel, published the Spectrum version at £7.95, and CRASH reviewed it in January 1985, giving it 98% for playability and for addictive qualities. One reviewer wrote that “it’s a long time since I’ve played a game as absorbing as this”. Front Runner’s advertisements led with the claim of a “superb scroll routine, described by experts as one of the best pieces of Spectrum programming ever”. Retro Gamer’s Stuart Campbell later pointed out that the Spectrum showed a smaller part of the cave than most versions, 16 by 11 squares against 20 by 12, and that its scrolling could not keep up when Rockford kept running. In June 1985 it stood ninth in CRASH’s chart, and in the summer of 1985 the readers of ZZAP!64 put it second only to Impossible Mission as their favourite Commodore 64 game.
Versions for the Apple II, MSX, Amstrad CPC and other machines followed. Mirrorsoft was selling Boulder Dash among its games in Amstrad Action in 1986.
Into the arcades
Boulder Dash went the unusual way, from home computer to arcade. In July 1984 ANALOG Computing reported that it “has recently been adapted for arcade use by Exidy”. Exidy’s Max-A-Flex cabinet was in effect an Atari 600XL running the ordinary cartridge, Retro Gamer explained, so the game was almost the same, except that coins bought time in 30-second units. In 1985 Data East made a new version with better graphics for its tape-loaded DECO Cassette System, on a vertical screen. Later in the 1980s Rockford appeared again in the arcades in Rockford, a game for the Arcadia system, which was built from Amiga technology and was then converted back to home computers.
Sequels and later versions
Boulder Dash II, called Rockford’s Riot on some machines and Rockford’s Revenge on others, followed in 1985. ZZAP!64 found it “not what it could have been”: sixteen new caves but few new features. It was the last Boulder Dash game Liepa wrote. First Star, he said, “thought it more important to promote itself as a developer, rather than promote me”, and after the second game he helped only with troubleshooting. In 1986 Electronic Arts sold the first two games together as Super Boulder Dash. Boulder Dash 3 moved the game into outer space, which Retro Gamer considered a mistake.
The Boulder Dash Construction Kit let players build their own caves. Epyx announced it in 1987 as one of the first releases on its lower-priced Maxx-Out label, for the Commodore 64, Apple II, Atari 8-bit and ST and IBM PC machines. It came with twelve new caves, but it was the editor that lasted, Retro Gamer wrote, “the foundation for countless ‘unofficial sequels’ for years to come”.
In 1990 came versions for the NES, by Data East, and the Game Boy, by Beam Software; both were built on the original caves, with lower jewel targets. The 2000s brought Kemco’s Boulder Dash EX for the Game Boy Advance (2002), a string of PC games, mobile versions and Boulder Dash: Rocks! (2007) for the DS and PSP.
In September 2017 the German publisher BBG Entertainment announced that it had bought the Boulder Dash rights from First Star Software. Its Boulder Dash Deluxe for PC and consoles included “Liepa World”, twenty new caves designed by Peter Liepa himself. BBG showed Boulder Dash 40th Anniversary at gamescom in 2024, with 60 caves from the first three games and new ones, and announced its full release for 21 August 2025.
Imitators
Boulder Dash became one of the most imitated games of its time. Edge named Superior Software’s Repton on the BBC Micro and Kingsoft’s Emerald Mine series among its commercial rivals, and Artsoft’s free Rocks’n’Diamonds (1995), with tens of thousands of levels made by its players. Retro Gamer counted almost 300 known clones in 2008. Liepa himself left the games industry after Boulder Dash II and spent many years working on 3D graphics software at Alias and Autodesk, the makers of Maya.
Sources
- Retro Gamer issue 27 (2006), pp. 24–27, “The Making of: Boulder Dash”: Liepa’s interview (the Atari 800, Chris Gray’s BASIC demo, The Pit, the cellular automaton, jewels and risk, the cavern definition language, the “granny” cave, Rockford’s idle animation and the scrolling, his later career); the Rockford arcade game.
- Edge issue 220, November 2010, pp. 103–105, “The Making of… Boulder Dash”: Liepa’s background, the original publisher and “the man”, doubling the graphics, two hours a day for six months, Forth, the release and conversions, Repton, Emerald Mine and Rocks’n’Diamonds, his later career.
- ANALOG Computing issue 20, July 1984, p. 19: Tom Hudson’s review (prices, sixteen caves, intermissions, Exidy’s arcade version).
- Electronic Games vol. 2 no. 14, September 1984, pp. 34–35: Tracie Forman’s review.
- Personal Computer Games issue 13, December 1984, pp. 85 and 88: Commodore 64 review and Game of the Month (Statesoft, £8.95/£10.95; the rules panel; Peter Connor’s review).
- CRASH issue 12, January 1985, pp. 73–75: Front Runner advertisement and Spectrum review (K-Tel, £7.95, ratings). CRASH issue 17, June 1985, p. 69: chart. Sinclair User issue 34, January 1985, p. 69: Front Runner advertisement.
- ZZAP!64 issue 3, July 1985, pp. 28–29: Rockford’s Riot review. For the readers’ vote of 1985, see the Impossible Mission entry.
- Commodore 64: A Visual Commpendium (Bitmap Books, 2014), p. 18: Liepa on the C64 conversion.
- Retro Gamer issue 53 (2008), pp. 32–41, Stuart Campbell’s Boulder Dash series history: the clones, the Spectrum scrolling and screen size, the Exidy and Data East arcade versions, Boulder Dash II and Super Boulder Dash, Boulder Dash 3, the Construction Kit, the NES and Game Boy versions, EX and the PC games, Rocks!.
- Retro Gamer: The Commodore 64 Book (2012), pp. 96–97, First Star Software history: Liepa at Alias/Autodesk.
- Compute! issue 87, August 1987, p. 39, and Compute!’s Gazette issue 51, September 1987, p. 28: Epyx’s Maxx-Out range and the Boulder Dash Construction Kit.
- For Mirrorsoft’s 1986 advertisement, see the Mirrorsoft entry.
- BBG Entertainment, “Boulder Dash is now owned by BBG Entertainment”, 19 September 2017; “Boulder Dash Deluxe now available for PlayStation!”, 21 May 2024; “Boulder Dash 40th Anniversary: Early Access now available”, 15 January 2025 (web, secondary). https://bbg-entertainment.com/boulder-dash-is-now-owned-by-bbg-entertainment/
- Games Press, “World premiere of BOULDER DASH 40th Anniversary at gamescom” (BBG press release, 2024; web, secondary). https://www.gamespress.com/World-premiere-of-BOULDER-DASH-40th-Anniversary-at-gamescom-Quiz-with-
- Chalgyr’s Game Room, “40th Anniversary Boulder Dash is Racing to PC…”, July 2025 (web, secondary): the release date of 21 August 2025. https://www.chalgyr.com/2025/07/news-boulderdash40-release.html