Lunar
Lander -
Celebrate the 40th anniversary of the moon landings with a more-real
than average game.
40 years ago Neil Armstrong may or may not have fluffed
his lines as he stepped on to the moon. Could the anniversary
be a better cause to do a Lunar Lander arcade game? Lunar
Lander is my second "hand made" arcade machine, and is joins its cousin
Cyclepong
on Southwold
Pier.
I love Apollo era technology - all those banks of gages and switches
and lights that flash. Very tactile unlike today's uniform
monitors . Thunderbirds and other TV programmes of my
childhood
created a vision of a technical future that's so much more exciting
that what we actually ended up with. For Lunar Lander I wanted to make
a game that gives a friendly nod the past and also provides a
different kind of entertainment to kids used to the sophistication of
modern computer games.
To land on the moon the Apollo astronauts had to use rocket thrust from
the landing module to balance the gravitational pull, while also
managing their landing position and fuel consumption. A tricky task (so
much so that Apollo 11 landed with only 15 seconds of fuel remaining).
This kind of moon landing inspired some of the very
first computer games.
The defining "Lunar Lander" game was Atari's vector graphics version
from 1979. The floating motion of the lander and the smoothness of the
vector graphics make it a hypnotic machine.
My lunar
lander (with spot-lights).
[Click image for full size]
Lunar lander cabinet
[Click image
for full size]
Make it real
Replacing
Atari's vector graphics, my Lunar Lander is a model that hangs on
fishing line and flys over a paper mache landscape. Stepper motors
provide accurate control of the position and a servo controls the
rotation. I won't claim the beautiful model making achieved
by
Thunderbirds, but the space-age look and visible wires certainly give
it something of that feeling.
Big dials (controlled by more servo motors) show the speed and fuel.
These are backlit with LEDs that change colour when in the
critical zone. Matching 'vintage' meters show the position and
rotation of the lander model. Adding to the historical look there is
a nixie
tube
display for the score. Lastly I couldn't quite get away without using a
monitor, so there is a small LCD which has been masked off to give it
an interesting aspect-ratio.
A car steering wheel (actually from a 2 CV) is used to turn the lander
with a simple button to fire the rocket. There is something magical
about turning the wheel and seeing the model copy the turn. The best
thing about showing the game is watching kids and adults
getting
transfixed. Having something real that moves adds something that the
millions of pounds spent developing today's games can't match. With
tongue in cheek the attract mode
advertises "latest 3D technology".
Lander model, gages and landscape
[Click image
for full size]
Watch your speed
[Click image
for full size]
Make
it special
Everybody
in business wants "stickiness". How do you keep people using your
product and not wandering off to the competition? Lunar Lander has a
particular problem here - in a physical model you can't keep inventing
new challenges like you can on a video game. Fortunately some lunchtime
discussions came up with a master plan that provides a nice end to the
game and an incentive to play again. Anyone who successfully lands on
the three landing sites will be rewarded with a "special medal" (it's
a badge actually), and there are four designs so even if you've done it
once you may still want to try again.
Last
but not least, the media loves to say that we live in a "celebrity
obsessed world" (this means that they are obsessed with celebrities).
Whether this is true or not, a famous name does help get attention -
particularly when there is real talent there too. Only the best is good
enough for Lunar Lander and due to a happy alignment of the planets Emma Freud was kind
enough to record the voice samples. Players can enjoy her superbly
weighted delivery instead of my mumbles.
Medals
awarded for completing all three levels
Make
it work (detail
for the techies!)
I
started thinking about Lunar Lander and acquiring parts in spring 2008,
and started making things in early winter. To have something that was
portable and easy to test with, I started out with just the mechanism
and landscape as a unit. This would just about fit in my study so I
could do the software indoors over the winter. The working prototype
was ready in time for Maker Faire UK in March
2009. Final construction of the arcade version went on until summer
2009.
The
electronics for Lunar Lander are based around ATMEL AVR
microcontrollers. An Arduino board acts as a convenient USB to serial
converter which makes the computer interface nice and easy. All the
microcontrollers listen to a common bus from the Arduino. The circuit
boards are hand-wired on stripboard or tripad except for the nixie
driver which needed a PCB to make the connections to the valve base of
the nixies. I was trying to make life easy for myself by using lots of
off-the-shelf parts. There is some slightly clever stuff in the AVR
software which makes the stepper motors run very reliably at the right
speed even if the speed is being varied during the game.
Infrared
sensors are used to detect the limits for the system. On power-up the
game does a calibration to find out the positions on all the limits.
After this it relies mostly on the stepper motor counts being correct
to measure the position of the lander. This seems to work fine - even
over very long runs of many hours. The speed and acceleration of the
stepper motors are controlled to make sure that no stalls or
missed-steps happen.
The
intelligence for the game and overall control is done on a PC. To try
and save time I used Python as the development environment with PyGame
providing the game framework. I really enjoyed Python. The power of the
language and the range of libraries do make it a good for doing lots of
work quickly.
The
mechanical parts came from various DIY stores, online shops and car
boot sales.
Construction was done with normal DIY tools but I did invest in a few
things to make this easier. An electric mitre saw is
invaluable for making good cuts, and a high quality cordless drill and
screwdriver really speed things up.
During the testing the mechanics have stood up pretty well. We'll see
how well they survive the continuous use on the pier.