Cart #21242 | 2016-05-24 | Code ▽ | License: CC4-BY-NC-SA
2

I was playing with the sprite editor, and found my creatures nice enough to make a game.
I'm still focused on my lode runner project, so I wanted to keep it short and simple.
this won't be the game of the year, and to give it a use, I did my best to document the code so eventually it can help beginners.

the game is simple (boring ?) - fire and hit a max. of alien before you die
but there's room to improve it :

• increase the difficulty by adding new aliens every 10 points
• move the aliens in direction of the player when it is at a certain range
...
 ```function new_alien() a={} -- a new alien is allocated a.x=rnd(120) -- aliens appear on the top 1/3 of the screen a.y=rnd(40) a.spr=flr(rnd(6))+2 -- and can be of any of the 6 alien sprites a.dx=rnd(4)-2 -- direction and speed is random a.dy=rnd(5)-2 -- but more often going down than up add(aliens,a) -- the new alien is added to our list of aliens end function _init() -- called once at the start of the programm x=60 -- player's fighter initial position y=100 hold_fire=0 -- used prevent continuous fire score=0 best=0 -- the high score bullets={} -- list of active bullets aliens={} -- the list of aliens for i=1,20 do new_alien() end -- creates 20 aliens cls() -- clear the screen print("saccharine",44,38,7) -- and displays a title screen print("PRESENTS",48,48,6) print("until death",43,58,8) print("x start",50,98,6) while not btn(5) do end -- waits for x key to be pressed end function _draw() cls() -- clear the screen spr(1,x,y) -- displays player's fighter sprite for a in all(aliens) do -- for each alien, a.x+=a.dx -- calculate its new position a.y+=a.dy if a.x>0 and a.y>0 and a.x<127 and a.y<127 then -- if alien is still inside the screen spr(a.spr,a.x,a.y) -- displays it if a.x+2>=x and a.x+2<=x+7 and a.y+2>=y and a.y+2<=y+8 then -- alien collision with fighter del(aliens,a) -- remove the alien from the list of aliens (we won't display it anymore) new_alien() -- and replace it by a new one so that the number of aliens is always the same sfx(2) -- louder crash sound than for the aliens x=60 -- respwan y=100 bullets={} -- clears all active bullets score=0 -- start over end else del(aliens,a) -- alien leaved the screen, delete it new_alien() -- and replace it by a new one end end for b in all(bullets) do -- parsing each active bullet b.y-=3 -- move it up if b.y<0 then -- the bullet exits the top of the screen del(bullets,b) -- we remove it from the list of active bullets else if pget(b.x,b.y)!=0 then -- if it hits something del(bullets,b) -- we delete it sfx(1) -- alien explosion score+=1 for a in all(aliens) do -- search which alien we killed if a.x<=b.x and a.x+5>=b.x and a.y<=b.y and a.y+4>=b.y then del(aliens,a) -- delete it new_alien() -- and replace it by a new one end end else pset(b.x,b.y,7) -- displays the bullet pset(b.x,b.y+1,8) -- and a red dot behind it end end end if (score>best) best=score -- displays updated high score, and current score print(best,0,0,6) print(score,0,8,6) end function _update() if (btn(0) and x>0 ) x-=2 -- going left if (btn(1) and x<120) x+=2 -- right if (btn(2) and y>50 ) y-=2 -- up if (btn(3) and y<120) y+=2 -- down hold_fire+=1 -- increases the timer 30 times per second if (btn(4) or btn(5)) and hold_fire>8 then -- allowed to fire again sfx(0) add(bullets,{x=x+1,y=y}) -- left gun add(bullets,{x=x+5,y=y}) -- right gun hold_fire=0 -- the timer is reset to zero, so we have end -- to wait it reaches 9 to fire again end ```

read the code, make it yours, improve the game, show off your changes and explain how you did
... or beat the score

Like you said, pretty simple, yet really fun and addictive game. I don't have PICO-8 yet, will have it once I get my PocketCHIP, and after that I will try to improve this and offer a different version c:

This code is very useful to beginners like myself. I'm new to creating and destroying objects in most languages, it's nice to have a solid example.