ZX81 Lunar Lander
A downloadable game
Guide the Lunar Excursion Module down to the landing zone safely. The landing zone is marked by five inverse video L's.
You start in the lunar approach phase which is program 64. During this phase the top number in the AGC readout shows the forward velocity decreasing, when it gets to zero the AGC switchs to manual landing and YOU are in control!
To complete a successful landing you must have zero forward velocity, and an altitude rate of no more than 1. The right hand portion of the screen has a semi authentic Apollo Guidance Computer readout - which is set to the PROG 66, VERB 6, NOUN 60 - these are the same as in the real Apollo mission.
PROG 66 is the program ran when in the "terminal descent stage" of the landing
VERB 06 means display values
NOUN 60 means terminal descent monitor
The three numbers below that are "Forward Velocity", "Altitude Rate", and "Altitude"
This is a real time lunar landing game, none of the old "enter a thrust value, then wait to see the new calculated positions"
Download
Install instructions
If you have a real Sinclair zx81, you need to use a 16K of RAM pack. Download the file lander.p if you have a tzxduino or similar way to load .p files.
OR...
download the .wav file and play that audio file into the zx81 as you would normally load a tape (LOAD "", then press play)
If you have an emulator installed on your PC or Mac such EightyOne
(https://sourceforge.net/projects/eightyone-sinclair-emulator/) then download the lander.p and open in the emulator.
The keys are keys:
Z left
M right
N fire main engine
Comments
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more changes including score of win vs crash :)
UPDATE:
Added an AGC program 64, which in Apollo mission is the LM Approach phase. It's kind of like an intro where the counter count down on the AGC display planel, and is hands free. The fuel only starts going down when the AGC program changes to 66. Hope you enjoy :)
have changed the code to increase the speed (and uses a video sync delay rather than wait loop which is better. So this runs faster now, previously (and the video) show it running at same speed; however I had wrongly got my emulator running faster than realtime lol
Hoping to produce updates to this which improve the game from its current, fairly basic level. I'd like to add iteraction with guidence computer, better phydics, more "realistic" values for the flight data display, and other instrument/sensor simulated readouts