Thanks Scott! Your compliments mean a lot 
I just updated the GIF for the racing game to feature a better car sprite. Next I want to redo the controls to allow drifting/skiding.
Anyway, you can define your own fill patterns with playdate.graphics.setPattern(pattern) I saw a use of that in the Asheteroids example. I used macOS calulator binary mode (click the digits inside the red highlight to "set pixels") and you'll see the number 0xF0 corresponds to 1111 0000. Do this 8 times to define 8 rows of pixels.
So this sort of pattern means you can do "marching ants" quite easily with the following pattern applied to narrow lines.
pattern = { 0xF0, 0xE1, 0xC3, 0x87, 0xF, 0x1E, 0x3C, 0x78 } -- diagonal lines
if ticks % 10 == 0 then
table.insert(pattern, 1, table.remove(pattern)) -- rotate rows to animate pattern
end
playdate.graphics.drawRect(10,10,380,220) -- draw single pixel rect
Example:
