Workshop

Backwards compatibility comes with a steep cost, and Android has chosen to bear the burden of that cost, whereas Google insists that you, the paying customer, bear that burden.

The math behind the game is atan2 which I use to get the angle from a thing to another thing:

function ato(from,to)
  return atan2(
    to.x-from.x,
    to.y-from.y
  )
end

And then when you give that angle to cos for the x axis and sin for the y axis you get (x,y) coords that can be multiplied by the number of pixels you want to "move" in that direction. So this function assumes a table like {x,y,a,s} and returns new a new x,y multiplied by s for "speed"...

function amove(●,s)
  s=s or ●.s
  return ●.x+cos(●.a)*s,
    ●.y+sin(●.a)*s
end

I use both those together like this to move the worms each frame. (This symbol: ∧ looks more like a worm in the Pico-8 font. If you didn't notice I like the emoji for variables 😋)

for ∧ in all(∧s) do
  ∧.a=ato(∧,웃)
  ∧.x,∧.y=amove(∧)
end

The astitue reader may have noticed amove allows one to supply their own s instead of the table's s... this is useful when you want to calculate things along something like a line, I mean the length of a worm. For example if we put everything together then we get this loop that, after a bullet (✽) moves, checks every part of a worm (for ∧t=0,∧.l do where ∧.l is worm length and ∧t is each "tail" pixel) and if they collided deletes both and plays a sound effect. amove is given each ∧t but it's not actually used to move the worm, just to reconstruct it's body for collision detection.

for ∧ in all(∧s) do
    for ∧t=0,∧.l do
      ∧x,∧y=amove(∧,∧t)
      if flr(✽.x)==flr(∧x)
        and flr(✽.y)==flr(∧y)
      then
        del(bullets,✽)
        del(∧s,∧)
      if #∧s==0 then
        sfx(2)
      else
        sfx(1)
      end
    end    
  end
end

A really nice summary of Linux troubleshooting triage that I've been using as a reference for years.