HOME COMPUTING WEEKLY, 6 Decemeber 1983, No. 40, Page 18 and 19
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Not one, not two... ...but three games to fit into your 1K ZX81. Philip
Moriarty explains what they are and how to play them

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Space Run (Philip Moriarty, 1K ZX81)
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In this moving graphics game, you have to steer your ship through an asteroid
field, picking up aliens and trying to keep your fuel from running out.

The aliens give you 10 credits every time you pick one up, and the amount of
credits you have at the end is your score.

The game ends in one of two ways - when your ship crashes into an asteroid or
when you run out of fuel.

When you have less than 20 units of fuel left, your ship changes into an
inverse X.

The only way to keep your fuel level up is to crash into one of the fuel
dumps (inverse F) which are worth 20 points.


How it works
------------
10-40   initialise variables
50-70   print ship, asteroids, fuel and aliens on screen, move ship, and
scroll screen up
90-101  decrement fuel, check fuel level and act accordingly
105-150 check to see if the ship has collided with anything, act accordingly,
return to line 50
210-280 end routine

Graphics symbols used
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CHR$ 187 or CHR$ 189 your ship
CHR$ 139 alien
CHR$ 23 asteroid
CHR$ 171 fuel dump

Variables
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HI hi-score
S  score
A$ CHR$ used for ship
F  fuel
P  PEEK to check if the ship has collided

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Simon (Philip Moriarty, 1K ZX81)
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A 1K version of the popular Simon memory game. I have used letters in this
version.

Most people know the rules, but here is a brief resum.

The computer displays a letter - type it back in.

If you do this correctly the computer adds another letter and so on - until
you finally type in a wrong code.


How it works
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2-20    sets up introduction and lets score=0
30-57   picks a random letter, adds it to the code, dispalys code on screen
for a short time
60-90   input your answer, check it, if it's right increment score and GOTO
40, if not GOTO 150
150-180 "lost" routine

Variables
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S  score
A$ code
G  control variable of loop for pause
B$ your answer

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ZX Pontoon (Philip Moriarty, 1K ZX81)
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This is an implementation of the popular card game Pontoon, where the players
try to get as close as possible to a total of 21.

You always play first, and if you exceed 21 the ZX81 wins automatically.

When you input S the ZX81 starts, and keeps going until it beats your total,
and therefore wins, or exceeds 21 and "busts".

There are 10 rounds to a game, and in my experience the ZX81 usually wins at
least five of them.


How it works
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1-6     intialise variables
15-70   main game section (for human)
100-150 ZX81 victory
200-250 main game section (for ZX81)
300-330 draw
400-420 human victory
430-470 end of game

Variables
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HV number of human wins
ZV number of ZX81 wins
G  control variable of "round" loop
A  total of human's cards
U  total of ZX81's cards
H  human's card
M  ZX81's card