Pac-10Liner

Copyright © 2024 by Víctor Parada

This is a little game for the 2025 NOMAM's BASIC 10-liners Contest. This program fits in the PUR-120 category, and it was written using FastBasic 4.6 for the 8-bits ATARI XL/XE computers line. Development started on 2024-03-29, and it took 2+2+1 days. The final version's date is 2024-04-08.

Description

Avoid Blinky while clearing the row of dots, but you can catch him after eating the power pill.

Instructions

	Press the button to start.
	You are Pac-man on the left side, Blinky is at the right one. Both will run against each other. Press the button to turn around and avoid Blinky.
	Escape through the sides. Blinky won't follow you through that path.
	When you eat the power pill, Blinky will be scared for a moment and you can catch him while he is purple.
	Scoring: At level 1, each dot gives 1 point, power pill gives 4 and the purple ghost gives 20. These points are doubled in level 2, tripled at level 3 and so on.
	Each time you eat all the dots of the row, the difficulty level will be increased a bit: the time for purple ghost will be shorter and the speed of Blnky will increase.
	There is only one life. The game is over when Blinky captures you. Press the button to try again.

Development of the game

A ZPH show featured a WIP game called "Pac-Line 2600" for the Atari 2600 console, the first game programmed by the host James Earl O'Brien. In a previous talk with him, while the game was a secret, he told that this game could be written as a tenliner, and I said that I could try to port it during the show when he had revealed it. During the show, he explained that this game was a port from "Pac-Line", a PICO-8 game by sizescape, which is an enhanced port of "Paku-Paku" by Kenta Cho, a web game released on January 2024.

Original Paku-Paku game.

Current Pac-Line version for PICO-8.

First public 2600 version by James.

I started the development during the show, but the design of the required bitmaps took more time than expected, so I couldn't have a working proto before the end of the show. Anyway, some hours later I could publish in the forum thread a video of my first prototype. Even though both Pac-Line and James' version used the joystick to move Pacman, I decided to use the single-button approach of Paku-Paku; this means that you only have to press the button to change the direction, since Pacman is always moving to either side. The next day, I made major improvements and had a new playable prototype. Before publishing it, I wanted to know the effect about that in the context of the Tenliners Contest. Bunsen from NOMAM confirmed me that this won't invalidate it as an entry for next year's contest, so I published a second video for the current prototype.

Initial prototype.

Second playable prototype.

The following updates were the fine tunning the difficulty increase and to add sound effects. The game started easy enough to learn the mechanics, but the difficulty slowly increased up to the crazy level 25, where it could not be beaten, as the ghost speed doubles Pacman's. On each level the earned score is multiplied by the level number, so it would increase a lot on faster levels. When reaching level 25, if all the ghost were captured, the score should be 11700 points. Any aditional points from there would be considered lucky ones. So, the objective of the game is to capture all the ghosts before reaching the last level, with the purpose of maximizing the score before the end of the game.

But while testing, I found that it was too easy to master the game and to reach to the crazy level, and I wanted to change that by doubling the speed: instead of to move one pixel at a time, move two. The result was a very fast game, a bit harder to master and to reach the top level. In my opinion, it a was better gameplay, and I left it.

After couple of days tweaking and commenting the code, I could have a working release candate with sound FX. I sent it to some friends (including James) to betatest it and receive some feedback.

New bitmaps and new name.

As I recalled that James prefered the joystick approach instead of a single-button one, I changed this for him, and found that I could save one byte of source code by doing this (and four more at the variables initialization because a control variable to avoid continuous side change by not releasing the button was not required). So, either way, the game was still a tenliner, so I decided to include both versions in the distribution disk, but I'm not sure which version will be submitted to the contest.

The final tweaks were palette for the NTSC version and some changes in the bitmaps that look better on the faster version. BTW, there are no timers based on the refresh rate of the TV system, so both PAL and NTSC versions should run at the same speed.

Some months later, I was invited to give a talk at the ExpoAtari Chile 2024. As an aditional event activity, I proposed the "Pac-Line Challenge", a free competition for the attendants, with a single try of the game trying to beat a record from others in a time frame. It was approved, so I prepared two things: a prize and a special single-button controller. At the event, we decided to project the screen to a wall for everyone to see it. Some people really wanted to win and after each try, they went to the end of the line to try again. After an hour, the challenge was closed and we had a winner. The prize, a specially printed mug, was given to him as a trophy at the end of the talk.

A special single-button controller.

People trying to beat the high score.

The projected playfield.

Felipe Sánchez was the winner of the trophy with 6905 points.

Download and try

Get the PACLINE.ATR file and set it as drive 1 in a real Atari (or emulator). Turn the computer on and a menu should start after the loading completes, then use computer console keys to select between PAL and NTSC, and from single button and joystick mode to control Pacman. A joystick in port 1 is required.

The code

The abbreviated BASIC code is the following:

The full and expanded BASIC listing is:

a=adr("{binary data}")+1

p=a+33

g=p+27

f=g+27

e=$2451

graphics 8

graphics 29

pmgraphics 2

move f+18,704,8

move $E000,$7000,512
move a,$7008,24

poke 756,$70

a=dpeek(560)+7
poke a,7
poke a+6,7

m=dpeek(88)+184

position 4,2
print #6,"{binary data}"

mset m-41,33,3
mset m+39,33,3

mset pmadr(3)+57,6,126

do

  while strig(0)
  wend

  x=0

  y=62

  o=1

  q=6

  l=0

  n=0

  h=0

  k=0

  j=0

  s=0

  r=0

  z=0

  v=0

  w=0

  repeat

    if n=0

      a=rand(5)*2

      poke m,1

      move m,m+2,29

      poke m+2+a+18*(x<31),2

      inc r

      if q and r&3=0 then dec q

      n=16

    endif

    v=not v

    w=(w+1)*(w<q)

    if v=0

      t=(t+1)&3

      x=(x+o+62) mod 62

      move p+9*o*(t/2),pmadr(0)+55,9

      pmhpos 0,x+x+61

    endif

    c=m+x/2
    a=peek(c)
    if a
      i=a*a

      if a=2 and not k then j=24+q*4

      poke c,0

      exec _s i

      dec n

      z=5+i

    endif

    if w=0 or k and v

      if k

        b=sgn(k-1-y)

        if b

          y=y+b
          exec _g g,e-b*$1B,0,y+y+61,0

        else
          k=0

        endif
      endif

      if not k

        u=not u

        if j then dec j

        b=sgn(x-y)

        if j

          if y<61 and y then y=y-b

          poke 705,
            $66+(j&4)*(j<24)*2

          exec _g f+9*u,0,y+y+61,0,
            y+y+61

        else

          y=y+b

          poke 705,$24

          exec _g g+9*(b+u),
            e+((b=0)-b)*$1B,y+y+61,y+y+61,0

        endif
      endif
    endif

    if z then dec z
    sound 0,40+z*2*i,10,z

    poke 77,0

    if strig(0)

      l=1

    elif l

      o=-o

      l=0
    endif

    h=abs(x-y)<3 and not k

    if j and h

      j=0

      h=0

      k=1+61*(y<32)

      exec _s 20

    endif

  until j=0 and h

  for a=0 to 9
    sound 0,8+a*8,6,8
    poke pmadr(0)+55+a,0
    pause 2
  next a
  sound

loop

proc _g a b c d dd

  move a,pmadr(1)+55,9

  dpoke pmadr(2)+57,b

  pmhpos 1,c
  pmhpos 2,d
  pmhpos 3,dd
endproc

proc _s a

  s=s+a*r
  position 25,7
  print #6,rtab(32) s
endproc

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