Fly Hunter 10L

Copyright © 2024 by Víctor Parada

Fly Hunter

This is a little game for the 2024 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 2024-03-07, and it took 4 days. The final version's date is 2024-03-14.


Catch as many flies in a row hanging with your web. Beware, the frog is lurking from the puddle.


FLYHUNT start The puddle is always full of flies. Press the button to begin the hunt!
FLYHUNT move You are the spider over the tree branch and you have to catch every single fly. You can move to the left and to the right through the branch using the joystick.
FLYHUNT hang With the button, you can hang using your cobweb and go down to catch the flies. You earn a point for every fly you catch.
FLYHUNT frog There is a frog hidden in the puddle. You can see it peek out when you are close to it.
FLYHUNT jump Sometimes, the frog will jump out of the water trying to eat you. Avoid hanging where the frog is lurking.
FLYHUNT end There is only one life. The game is over when the frog eats you or when you miss a fly. Press the button to try again.

Development of the game

A ZPH show featured a WIP game called "Fly Hunter" for the Atari 2600 console that was very attractive. It was published by 8bitPoet in the AtariAge forum. It started as a very simple gameplay, but it got many new elements soon after some comments of the community. The version that was presented in the show had many simple animations that improved the gameplay.

Initial 2600 version

Initial 2600 version by 8bitPoet, with a worm as the enemy.

Current 2600 WIP

Current WIP version, using a frog instead of a worm.

I was impressed by the game and I thought that I could port it as a simple BASIC tenliner, so I started a prototype. The first thing I did was to design the sprite bitmaps. Using DLI feature of Fastbasic it could be simple to recreate the playfield, where I did the first animation: the frog jump, including the water splash. Then, I added the spider and made it move to the sides and to hang.

FLYHUNT prototype

Initial prototype of a jumping frog and a splash.

FLYHUNT prototype

Added the spider (showing one frame of the splash animation).

When I added the fly, I decided to change the bitmaps of the sprites, because I wouldn't use hitboxes but P/M collisions, and that required to separate the spider from the web and use two different P/M graphics in order to not caprure the fly using the web while hung. I added the score, but immediatelly noticed a problem: no more room for more BASIC source code. At that point, the animations were nice, but there were no sound FXs and game dynamics were not the way I wanted. Almost everything moved at the same speed, fast, but difficult to play, so it also needed space for tweaking. I had to decide which features must be removed to recover some coding space, and the splash and the wavy fly gone away.

FLYHUNT prototype

New playfield, but less FXs.

After couple of days tweaking and commenting the code, I could have a working release candate. I sent it to some friends to betatest it and receive some feedback. A couple of hours later, I think I have it, and used the extra bytes to enhance some FXs.

Download and try

Get the FLYHUNT.ATR file and set it as drive 1 in a real Atari (or emulator). Turn the computer on and the game should start after the loading completes. A joystick in port 1 is required.

NOTE: This game is for PAL computers. Use the file FHNTSC.XEX included in the ATR to be played on NTSC computers.

The code

The abbreviated BASIC code is the following:

The full and expanded BASIC listing is:

Fly Hunter 10L
(c) 2024 Víctor Parada

P/M graphics
- P0: Frog
- P1: Fly
- P2: Spider
- P3: Web thread
No missiles are used.
d=adr("{binary data}")+1

0 (9 bytes): Spider in tree bitmap
6 (14 bytes): Falling spider bitmap
20 (6 bytes): Web bitmap
23 (32 bytes): Frog bitmap
55 (8 bytes): Display list portion with DLI enabled
63 (9 bytes): Color palette
move $E000,$7000,512
mset $7018,8,$FF
Copy the charset to RAM and replace one char with a block to draw the tree
graphics 18
poke 756,$70
Set up graphics mode 2 (ANTIC 7) 20x12 without text window
move d+55,dpeek(560)+7,8
Enable DLI bit on some DL lines
Pointer to the playfield
pmgraphics 2
Enable double line resolution P/M graphics
poke $D008,1
Set P0 (frog) double width
data c() byte=$8A,$B6,$84
dli set _d=c into $D01A
dli _d
Enable DLI to set playfield colors
move d+63,704,9
Set color palette
for b=0 to 9
  dpoke a+b*20+16,$8383
next b
mset a+21,19,$83
Draw the trunk and branches of the tree
position 3,5
print #6,"fly hunter"
Print game title
  mset pmadr(0),512,0
Clear P/M players area
  while strig(0)
Waiting for the fire button to start
Frog height
Frog horizontal position
  mset a+103,10,0
Clear midscreen message
  mset a+229,9,0
Clear score
Killed flag
Fly horizontal position
Fly speed
Frog and fly timer
Spider height (0 when it is at the branch)
Spider horizontal position
Force display of the spider
  poke $D01E,0
Clear P/M collisions
Update timer, iterates between 0 and 3
    b=strig(0) + k + z
Moving the spider?
Releases the button if killed (button is pressed when STRIG=0)
    if b=0 or y
Is the button pressed or already hanging?
      if b and y
Is the spider hanging and the button is not pressed?
        dec y
Return a step to the tree branch
      elif y<22 and not b
Is the button pressed and not at the bottom?
        inc y
Enlarge the thread one step
      if y
Is the spider hung?
        sound 0,10+y+y,10,y<22
Yes... turn on sound.
Precompute bitmaps and P/M destination area to display
P/M area of the spider
Bitmap of the hanging spider
P/M area of the thread
Bitmap of the tread
Size of the spider bitmap
Flag to use the walking spider bitmap
Walk only if not hanging
    if z
Put the spider over the tree branch.
P/M area of the spider
Bitmap of the walking spider
Size of the spider bitmap (including extra zeroes below to remove the last hung spider bitmap)
P/M area of the thread (using the blank area of the screen because there is no thread while walking)
Bitmap of the hanging spider
      sound 0
No sound
    if f=0 and abs(x-r)<3 and rand(9)<=y/4
If the frog is in the water and is almost below the spider, jump at a chance of 1/9 (or up to 6/9 if hanging)
Set frog height
Set frog jump flag and direction
    if m
Is a fly in the playfield?
Move it to the left at its current speed
      if m<30 then k=1
If the fly reached the left side of the playfield, the game is over
Need to put a fly
Set fly horizontal position at the right
Quick fly in a chance of 1/5
      dpoke pmadr(1)+40+rand(46),$0703
Put a fly at a random height
    if g
Is the frog jumping?
New height
Set the full frog bitmap to be drawn
      if f<8 then j=4*f
Is the frog still touching the water? Display only a portion of the bitmap
      sound 1,200-f*3,12,12
Jumping FX
      if f>20
Reached the top?
Change direction
      elif f=0
Returned to water?
Disable jump
        r=255-e mod 100
Move frog to the right (higher the score, closer to the center of the playfield)
        sound 1
Stop the jumping sound
Precompute P/M memory area to display the bitmap
    if not f
Move the frog in the water
      pmhpos 0,r
Follow the spider at 1/4 of the spider speed (every 4th frame).
      if abs(x-r)<20 then b=$1C14
      dpoke pmadr(0)+97,b
Show frog's eyes only if it is near the spider
    if peek($D00C)&4
Check if the frog ate the spider
Move the spider and cobweb out of the playfield
      sound 0
Stop hanging sound (if any)
      if f then g=-1
Let the frog return to the water
    if peek($D00D)&4
      sound 0,9,8,8
Check if the spider ate the fly
      mset pmadr(1),128,0
Move the fly out of the playfield to avoid double scoring after clearing collisions register
      poke $D01E,0
Clear P/M collisions
      inc e
      position 9,11
      print #6,e
Increase the score
    poke 77,0
Disable attract mode
    pause 0
Sync the frame to avoid glitches
    move s,t,u
    move v,w,6
    pmhpos 2,x
    pmhpos 3,x
Display the spider (and web thread)
    pmhpos 1,m
Display the fly
    if g then move d+23,i,j
Display the frog
Disable force flag to display of the spider over the branch
  until y+f=0 and k
Game loop ends when killed and the frog is not jumping and the spider is not hung
  position 4,5
  print #6,"game over"
Print Game Over message
  for b=2 to 8
    sound 0,b*30,6,13-b
    pause 5
    pause 2
  next b
Final sound FX
End of main loop

Return to my 10-liners page.

© 2024 by Víctor Parada - 2024-03-14 (updated: 2024-03-16)