10-liner: Fly Hunter 10L

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.

Description

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

Instructions

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.

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.

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.

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

	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
a=dpeek(88)	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
do	MAIN LOOP
mset pmadr(0),512,0	Clear P/M players area
while strig(0) wend	Waiting for the fire button to start
e=0	Score
f=0	Frog height
r=240	Frog horizontal position
mset a+103,10,0	Clear midscreen message
mset a+229,9,0	Clear score
k=0	Killed flag
m=0	Fly horizontal position
n=0	Fly speed
o=0	Frog and fly timer
y=0	Spider height (0 when it is at the branch)
x=99	Spider horizontal position
z=1	Force display of the spider
poke $D01E,0	Clear P/M collisions
repeat	GAME LOOP
o=(o+1)&3	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 endif	Enlarge the thread one step
if y	Is the spider hung?
sound 0,10+y+y,10,y<22	Yes... turn on sound.
t=pmadr(2)+y*3+17	Precompute bitmaps and P/M destination area to display P/M area of the spider
w=t+131	Bitmap of the hanging spider
v=d+20	P/M area of the thread
s=d+6	Bitmap of the tread
u=14 else	Size of the spider bitmap
z=1 endif	Flag to use the walking spider bitmap
else b=stick(0) x=x+((b=7)(x<166)-(b=11)(x>56))*2 z=1 endif	Walk only if not hanging
if z	Put the spider over the tree branch.
t=pmadr(2)+22	P/M area of the spider
s=d	Bitmap of the walking spider
u=9	Size of the spider bitmap (including extra zeroes below to remove the last hung spider bitmap)
v=a	P/M area of the thread (using the blank area of the screen because there is no thread while walking)
w=t+128	Bitmap of the hanging spider
sound 0 endif	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)
f=1	Set frog height
g=1 endif	Set frog jump flag and direction
if m	Is a fly in the playfield?
m=m-(o&1!n)	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
else	Need to put a fly
m=216	Set fly horizontal position at the right
n=rand(5)=0	Quick fly in a chance of 1/5
dpoke pmadr(1)+40+rand(46),$0703 endif	Put a fly at a random height
if g	Is the frog jumping?
f=f+g	New height
j=32	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?
g=-1	Change direction
elif f=0	Returned to water?
g=0	Disable jump
r=255-e mod 100	Move frog to the right (higher the score, closer to the center of the playfield)
sound 1 endif	Stop the jumping sound
i=pmadr(0)+99-f*4 endif	Precompute P/M memory area to display the bitmap
if not f	Move the frog in the water
r=r+sgn(x-r)*(o=0) pmhpos 0,r	Follow the spider at 1/4 of the spider speed (every 4th frame).
b=0 if abs(x-r)<20 then b=$1C14 dpoke pmadr(0)+97,b endif	Show frog's eyes only if it is near the spider
if peek($D00C)&4 k=1	Check if the frog ate the spider
x=0 y=0	Move the spider and cobweb out of the playfield
sound 0	Stop hanging sound (if any)
if f then g=-1 endif	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 m=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 endif	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
z=0	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 sound pause 2 next b	Final sound FX
loop	End of main loop

	The puddle is always full of flies. Press the button to begin the hunt!
	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.
	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.
	There is a frog hidden in the puddle. You can see it peek out when you are close to it.
	Sometimes, the frog will jump out of the water trying to eat you. Avoid hanging where the frog is lurking.
	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.