Forty Years of Lunar Lander

In 1969, an Apollo-crazy high school student wrote one of the most influential computer games of all time.

By  |  Sunday, July 19, 2009 at 11:54 pm

Lunar Lander

Lunar Lander games abound on every platform. Along with Tetris and Pac-Man, the game–in which your mission is to safely maneuver your lunar module onto the moon’s surface–is one of the most widely cloned computer games of all time. But did you know that game players began touching down on the moon in Lunar Lander just months after Apollo 11 astronauts Neil Armstrong and Buzz Aldrin did so on July 20th, 1969?

lunarlander_tinyToday’s versions of Lunar Lander are easily taken for granted; they’re generally regarded as dinky games you can get for free–“Who would pay for that?”

But the mother of all realistic space simulations wasn’t always perceived that way. In 1969, it was, in its own way, a sophisticated, ambitious piece of digital entertainment. And during the BASIC era of the 1970s and 80s, many programmers cut their teeth by attempting to program their own version of Lunar Lander. David Ahl, founder of Creative Computing magazine, called it “by far and away the single most popular computer game” in 1978 (and he was only talking about the text version!). Indeed, Lunar Lander was one of the early computer games that helped define computer games.

The Eagle Lands

YOU ARE LANDING ON THE MOON AND HAVE TAKEN OVER MANUAL
CONTROL 500 FEET ABOVE A GOOD LANDING SPOT. YOU HAVE A
DOWNWARD VELOCITY OF 50 FT/SEC. 120 UNITS OF FUEL REMAIN.

Among the millions who watched the Apollo 11 landing was a 17 year old Massachusetts high school student named Jim Storer. In the fall of 1969, around the time of the Apollo 12 launch, Storer took his inspiration to class with him. There, he programmed a simple text-based simulation of humanity’s greatest technological achievement on his school’s Digital Equipment Corp. PDP-8 minicomputer system.

“Lexington High School had a PDP-8,” Storer recalls. “It had 8 Teletypes, a small hard drive, and 12KB of main memory, where 8KB was used by the system and 4KB time shared by the users.”

Storer wrote his new program, “Lunar Landing Game,” in FOCAL, a programming language for the PDP-8 that was similar in some ways to BASIC (both were introductory languages known for their ease of use). His simulation was simple, yet powerful: underneath lay a realistic set of equations Storer believes his father may have taught him.

Lunar Landing Game’s gameplay consisted of a turn-based question and answer session, asking the user for the rocket fuel burn rate at each turn, which the user would then enter as a number from 0 to 200. The constraints against you were simple:

HERE ARE THE RULES THAT GOVERN YOUR SPACE VEHICLE:
(1) AFTER EACH SECOND, THE HEIGHT, VELOCITY, AND REMAINING FUEL WILL BE REPORTED.

(2) AFTER THE REPORT, A ‘?’ WILL BE TYPED. ENTER THE
NUMBER OF UNITS OF FUEL YOU WISH TO BURN DURING THE
NEXT SECOND. EACH UNIT OF FUEL WILL SLOW YOUR DESCENT
BY 1 FT/SEC.

(3) THE MAXIMUM THRUST OF YOUR ENGINE IS 30 FT/SEC/SEC OR
30 UNITS OF FUEL PER SECOND.

(4) WHEN YOU CONTACT THE LUNAR SURFACE, YOUR DESCENT ENGINE
WILL AUTOMATICALLY CUT OFF AND YOU WILL BE GIVEN A
REPORT OF YOUR LANDING SPEED AND REMAINING FUEL.

(5) IF YOU RUN OUT OF FUEL, THE ‘?’ WILL NO LONGER APPEAR,
BUT YOUR SECOND BY SECOND REPORT WILL CONTINUE UNTIL
YOU CONTACT THE LUNAR SURFACE.

Along the way, Jim Storer created one of the earliest computer games–one of a handful of text-based PDP-8 games of the 1960s, and one of the first computer simulation games ever. In less than 50 lines of code, Storer captured the imaginations of an entire generation of programmers with a gripping space drama composed of nothing more than simple text statements.

Storer submitted his game to PDP-8 maker DEC, which was always looking for innovative and interesting uses of its computers. The programs were usually distributed for free or used as demonstrations to potential clients, serving as a powerful marketing tool. At DEC, an employee named David H. Ahl translated Storer’s Lunar Lander into the BASIC language, which soon overtook FOCAL as the most popular introduction to programming. From there, both the FOCAL and BASIC versions of Storer’s simulation spread to other PDP-8 users through DEC’s EDU newsletter and through distribution by DEC’s Education Product Group.

Lunar Lander, 1969

After that, Storer forgot about the game. Life went on. He never sold it, and never followed the progress or influence of its imitators as they echoed down through the years. “After leaving high school I never thought about the game again,” says Storer. “Until about a couple of months ago when someone e-mailed me about this, I was completely unaware of any Lunar Lander game other than the one I wrote in high school.”

101 BASIC Computer GamesBut Storer’s computer experiences in high school shaped the rest of his career: “I became interested in computer science as a result of taking that computer class and doing programming on the PDP-8.” Storer later studied computer science as an undergraduate at Cornell University and then received his Ph.D. in Computer Science at Princeton University. He is now a professor of computer science at Brandeis University.

In 1973, DEC published a book edited by Ahl called “101 BASIC Computer Games” that included both Storer’s version of Lunar Lander and two others that had been inspired by Storer’s program. In 1978, Ahl revamped the book with a focus on home microcomputers that were common at the time, and it sold over a million copies. Thanks to Ahl’s book, Lunar Lander’s status as one of the classics of early computer gaming was assured.

Lunar Lander Gets Graphical

DEC consultant Jack Burness had long been a fan of America’s race to the moon. He recalls with great clarity the excitement of the period: “The space program was an incredibly big project then. More than a project, it was a national embracing of the future.”

Inspired by a co-worker who attended the launch of Apollo 16, Burness pestered his local senator for passes to see the launch of the final Apollo mission, Apollo 17, in December 1972. “A bunch of my friends went with me to see it,” recalls Burness. “It was the last launch and was at night–an overwhelming powerfully experience.”

That experience simmered in the back of his mind for the next few months, and it proved influential when DEC needed a software demo for its new GT40 terminal.

DEC GT40 Terminal

The DEC GT40 was a graphical computer terminal–unusual for its time, since it used a vector CRT display. One electron gun directly drew geometric shapes on the screen, providing a potent way to generate sharp, high-resolution computer graphics with the limited computing power available at the time. Conventional bitmapped raster displays (like those on conventional TV video games) draw the screen progressively from top to bottom, one row at a time, and required vastly more memory to compose a detailed on-screen image.

“I actually had quit Digital the previous spring and moved to Cambridge to consult for Draper Labs,” says Burness. “For some now long-forgotten reason I was back consulting to DEC that winter.”

1 2 3 4  NEXT PAGE»


49 Comments


Read more: , ,

35 Comments For This Post

  1. Seb Lee-Delisle Says:

    Hi there and thanks for the mention! A really interesting article, I never realised the game had a life before the arcade game.

    I’ve just finished a 3D Lunar Lander Flash game just in time for the 40th anniversary : http://www.sebleedelisle.com/?p=473

    cheers!

    Seb

  2. fogus Says:

    I wrote a DSL in the Scala programming language that implements a dialect of BASIC which I then used to write a textual Lunar Lander game. :)

    http://blog.fogus.me/2009/03/26/baysick-a-scala-dsl-implementing-basic/

    -m

  3. Dave Barnes Says:

    I went to work for DEC in 1976 and got to play Lunar Lander on a machine in the Mill. I always crashed.
    If you landed successfully there was a McDonalds on the Moon.

  4. Peter Says:

    @Dave Barnes
    there was a McDonalds on the Moon.

    If you landed near it, an astronaut exited the LEM and visited it.

    Played it at Westfield in 1976/7 and crashed, too. The tech who “owned” the system showed me the McDonalds, and helped me acquire enough scrap parts to build a VT05 to use for grad school

  5. Richard D Says:

    I used to play the GT40 version and there was a McDonalds somewhere on the lunar surface. If you landed close enough a little guy would walk to the arches and order two big macs and a cheeseburger to go. (Not 100% sure about the order!).

    R.

  6. Ralph Nevins Says:

    Hp-25 calculator had a simple version
    49 programmable steps
    circa 1975
    http://www.hpmuseum.org/software/25moonld.htm

  7. Jim Garrison Says:

    I played Lunar Lander on 12/24/1967, on a GE timesharing system (ASR33 teletype, 110 baud acoustic coupler modem). I was a fourteen-year-old and thought I was going to be a chemical engineer. My dad called from the office and said that computer time that day (normally $50/hour) was free and I should come down and play some games. After a few games of Lunar Lander and a football simulator I asked him how it worked, and he said “just type LIST”. The rest, as they say, is history. That day is etched in my memory, and is the day I decided to write software for a living, which I’ve been doing ever since. [The system used Dartmouth BASIC and I recall the Lunar Lander program was only a few hundred lines of code, of which over half was text describing the game.]

  8. Adrian Says:

    Here’s a nice implementation.

    http://www.lushprojects.com/lunarlander/

    It’s with some equally fine exhibits at Southwold pier

    http://www.underthepier.com/06_new.htm

  9. brianlj Says:

    @Jim: HP-25, eh? I wrote a version for the TI-59 a couple of years after that. Kept it on one of those little whizz back’n’forth memory cards.

    Been quite a while since I thought of that.

  10. Bill Marshak, Ph.D. Says:

    I was at Univ of Miami (FL) in 1970 when I played this game on Dr. Earl Winer’s Lab 8 computer (Industrial Engineering Dept). It was a hybrid PDP-8 and analog machine which used DEC Tape, random access tape, for bulk storage. It had a vector graphic CRT (not TV raster) display. You controlled the LEM using the toggle switches on the PDP-8 face. I believe it might have been written at MIT.

    If you landed sucessfully (horizontal and vertical velocity within tolerance and on flat surface), Armstrong emerged, planted a flag, and said One small step for man, one giant leap for mankind.” If you found the MacDonalds (complete with golden arches), he went into the the restaurant and ordered (I think) “a Big Mac to Go”. It was the first computer game I ever played, followed by the Colossal Cave on a PDP-11 and Pong.

    Very cool for the time!

    Bill Marshak

  11. Jon Thompson Says:

    Austin Meyers has a mars lander already built into X-Plane. He also talks about the physics of flight on mars here..

    http://www.x-plane.com/mars.html

  12. Matt Curtis Says:

    I developed a character graphics-based version for USCD Pascal in the early 80s at the University of Rochester.

  13. agent58 Says:

    Man I remember playing that game. Back then it was so cool.

  14. Bill H. Says:

    Played it on a GE TSS-8 (PDP-8 time sharing system) in 1974 at high school in Pittsfield, MA. There was a version that would report crater size if you crashed.

  15. TotalForge Says:

    I didn’t see this fine sim mentioned, if you have a windows machine you are in for a treat.

    http://eaglelander3d.com/

  16. Bill Baxter Says:

    What!? No mention of Gravitar!?
    http://en.wikipedia.org/wiki/Gravitar

    It was kind of a Lunar Lander + Asteroids hybrid. I never could get past the first level, but I loved that game for some reason.

  17. Bob Says:

    Oi! Tosspots! You’ve missed out an entire generation of these games between ’82 and ’90! Have you ever heard of 8-bit Thrust? Firebird released awful versions of this for C64, ZXSpec and AMX, none of which compared to the 16 bit mastery that was Oids. A fine retrospective on the early history, but there’s a whole generation missing here…

  18. BDD Says:

    I wrote a Lunar Lander years ago, for the TRS-80 Model III, in BASIC. I’ve had a similar game in the back of my mind, where the player would land on other planets, and in the case of the gas and ice giants, drop a probe into the atmosphere or jettison a satellite. If you got too far into the atmosphere, you’d be crushed. I may still write it one day; maybe for the Dreamcast, as a goof.

  19. Wout Mertens Says:

    This prompted me to hunt for a game for IBM that I absolutely loved: “Lunar Module”. I couldn’t find it unfortunately.

    You had to take off and land on a vector-based 2D moon surface, killing evil turrets that tried to shoot you down with bullets. It included a level editor, my favorite level was humongous and included some very steep drops. It had unlimited fuel and ammo so maybe it’s not a strict descendant. Must have been from around 1990.

    Ah the memories…

  20. writer Says:

    hey there

    awesome write up

    A really interesting article

    keep penning more

    be well

    TD

    http://techdivine.com/tdblog

  21. Bruce B. Says:

    I remember a fantastic Lunar Lander simulator running on Control Data 6000 series mainframes around 1970 (one of the most powerful computer systems of the time [http://en.wikipedia.org/wiki/CDC_6000_series]) at Purdue.

    The operator’s console, consisting of two vector CRT displays was the interface. One display would be a view port out of the lander show a star-field and the moon; the other display was an instrument panel, all running in real time. Control was via assigned keyboard keys for fuel flow, thrusters, etc. I can’t tell you the number of hours “invested” in honing our skills of a very realistic, demanding program during non-production hours.

  22. Hypocee Says:

    My favorite adaptation for Windows is Gravity Well: http://www.plbm.com/gravwell.htm – analog thrust, classic graphics, progressively tough gravity.

  23. Stuart Halliday Says:

    I wrote a Lunar Lander graphics program for the Sharp PC1500 computer.

    I used the built-in BASIC and a bit of 6502C assembler to do the graphics. At first it was just a dot going left to right. As you got closer to the landing site, you turned the thin but wide display on its side to represent landing.

    All in 4K bytes…cor!

    Ahh we had so much fun in the 1980s.
    :-)

  24. kmoser Says:

    I still have a TTY printout of the source code as well as an instance of playing the game from 1980.

  25. Russ Greenlaw Says:

    The late 60s origin must be wrong. I played LL on a 1957 text-only vacuum tube and paper tape computer in 1964/65 period. Game had to have been well known (even public domain) by then, did require a dedicated or non-batch (that is interactive) environment; I played it on a machine with no operating system, just a floating point interpreter (a bit like a cross between assembler and BASIC); do not recall whether LL game ran under FP interpreter or was stand-alone. Game printed out a line at a time as you descended to the moon and adjusted your burn rate – looked pretty much like the BASIC run on the Atari listing under wikipedia. My guess LL dates from 1958 or perhaps 1960. Can anyone provide an older example ?

  26. Grant Philpott Says:

    What is the name of the Space Lander type game that also has Space Invader shapes attacking you? You had to land in about 3 places and also go up as well. It's such a long time ago!

  27. hulu downloader Says:

    It included a level editor, my favorite level was humongous and included some very steep drops. Feels Good.

  28. Cortex Says:

    You've forgotten a very very weird occurrence of that game :

    In the real Sega Pinball game Apollo XIII released in 1995, inspired by the motion picture, there was, outside the fabulous 13-ball multiball mode, a moon landing video mode…

    Smile!
    HB

  29. netflicks Says:

    Thanks for posting these Adrian
    Here's a nice implementation.
    http://www.lushprojects.com/lunarlander/

    It's with some equally fine exhibits at Southwold pier
    http://www.underthepier.com/06_new.htm

  30. dreambox dm600 pvr Says:

    That day is etched in my memory, and is the day I decided to write software for a living, which I've been doing ever sincet was kind of a Lunar Lander + Asteroids hybrid. I never could get past the first level, but I loved that game for some reason. i

  31. @SLPhysics Says:

    Hey, thkx, Ralph. I'm writing an academic paper about my Second Life lander simulator inspired in that version I used to play on my old HP25 and I needed that reference. You may have spared me a few hours of googling.

  32. Andy Pandy Says:

    i have a taito lunar rescue. cabinet machine. 1979. like to no more about it.

  33. Andy Pandy Says:

    I HAVE A TAITO 1979 LUNAR RESCUE. COCKTAIL MACHINE. I WOULD LIKE TO NO MORE ABOUT IT. I LIVE IN THE UK. MY NUMBER IS 07932836990. MY NAME IS ANDY

  34. Andy Pandy Says:

    i have a TAITO LUNAR RESCUE 1979 COCKTAIL MACHINE. LIKE TO NO MORE ABOUT IT. U CAN CALL ME ON 07932836990

  35. sh0v0r Says:

    Great Article, perhaps some if you guys might like to check out the game I am developing called Lunar Flight. http://www.shovsoft.com/lunarflight

14 Trackbacks For This Post

  1. World’s Oldest Time-Waster? Lunar Lander | Social Nibble Says:

    [...] beauty contests, and it has a pretty weak storyline unless you have a magnificent imagination, but Lunar Lander may well be one of the oldest time-wasters in [...]

  2. Top Posts « WordPress.com Says:

    [...] Forty Years of Lunar Lander Lunar Lander games abound on every platform. Along with Tetris and Pac-Man, the game–in which your mission is to [...] [...]

  3. World’s Oldest Time-Waster? Lunar Lander | DodaPedia Says:

    [...] beauty contests, and it has a pretty weak storyline unless you have a magnificent imagination, but Lunar Lander may well be one of the oldest time-wasters in [...]

  4. 40th anniversary of the moon landing | The Historical Webber Says:

    [...] from space computers to space computer games, the Technologizer has a great piece about a well loved space game, Lunar Lander. This game started out as a [...]

  5. Aaron’s blah, er, Blog » Remembering Apollo 11 Says:

    [...] for the nerds: Forty Years of Lunar Lander How They Built it: The Software of Apollo 11 How powerful was the Apollo 11 computer? Apollo [...]

  6. Računalniški muzej » 40 let Lunar Lander-ja Says:

    [...] Skoraj nemogoče je bilo v zadnjem mesecu prezreti evforično in medijsko izredno dobro pokrito praznovanje obletnice prvega človeškega pristanka na luni – Apollo 11. Ravno pod vplivom Apollo misij je najstnik Jim Storer sprogramiral eno izmed prvih računalniških iger – Lunar Lander v jeziku FOCAL. Jezik POCAL je bil napisan za Digitalove PDP-8 računalnike. Malo obširnejši članek na to temo: http://technologizer.com/2009/07/19/lunar-lander/. [...]

  7. Forty Years of Lunar Lander | Mr. Walker's Class Web Says:

    [...] Forty Years of Lunar Lander Forty Years of Lunar Lander [...]

  8. The First Great Computer Game -> Lunar Lander | Mr. Walker's Class Web Says:

    [...] The First Great Computer Game -> Lunar Lander Forty Years of Lunar Lander [...]

  9. Preview of ‘Lander Hero’ – A Charming Upcoming iPad Cave-Flyer | Touchfresh apps Says:

    [...] simple proposition there — it's just gravity and you. Lunar Lander, which got its start back in 1969, kicked off the cave-flyer genre that boasts many great games under its banner. iOS developer [...]

  10. Preview of 'Lander Hero' – A Charming Upcoming iPad Cave-Flyer | Spil og games Nyheder Says:

    [...] simple proposition there — it's just gravity and you. Lunar Lander, which got its start back in 1969, kicked off the cave-flyer genre that boasts many great games under its banner. iOS developer [...]

  11. Preview of ‘Lander Hero’ – A Charming Upcoming iPad Cave-Flyer – JailBake Says:

    [...] the simple proposition there — it’s just gravity and you. Lunar Lander, which got its start back in 1969, kicked off the cave-flyer genre that boasts many great games under its banner. iOS developer [...]

  12. Preview of ‘Lander Hero’ – A Charming Upcoming iPad Cave-Flyer | TouchArcade.ru Says:

    [...] simple proposition there — it's just gravity and you. Lunar Lander, which got its start back in 1969, kicked off the cave-flyer genre that boasts many great games under its banner. iOS developer [...]

  13. Preview of ‘Lander Hero’ – A Charming Upcoming iPad Cave-Flyer – Mudojuegos Says:

    [...] the simple proposition there — it’s just gravity and you. Lunar Lander, which got its start back in 1969, kicked off the cave-flyer genre that boasts many great games under its banner. iOS developer [...]

  14. Preview of ‘Lander Hero’ – A Charming Upcoming iPad Cave-Flyer | RemoveWAT SP1 Says:

    [...] the simple proposition there — it’s just gravity and you. Lunar Lander, which got its start back in 1969, kicked off the cave-flyer genre that boasts many great games under its banner. iOS developer [...]