Quick and dirty PICO-8 script to let my artist roommate animate the sprites he's been making.

simple_pico_animation_helper.lua

function _init()
	--enter the frame numbers
	--in the order you want
	--inside the {} separated
	--by commas
	sprite_sequence={16,17,18,19}
	--enter the direction you
	--want the sprite to travel
	--inside quotes, "right"
	--or "left"
	heading="right"

	p={
		x=60,
		y=88,
		sp=sprite_sequence[1],
		sseq=sprite_sequence,
		idx=1,
		anim=0,
		hding=1
	}
	if heading=="left" then
		p.hding=-1
	elseif heading=="right" then
		p.hding=1
	end
	cls()
end

function _draw()
	cls()
	rectfill(0,96,127,127,3)
	spr(p.sp,p.x,p.y)
	
	if time()-p.anim>.1 then
		p.anim=time()
		p.x+=(1*p.hding)
		if p.hding==1 then
			if p.x>128 then
				p.x=-8
			end
		elseif p.hding==-1 then
			if p.x<-8 then 
				p.x=128 
			end
		end
		
		p.sp=p.sseq[p.idx]
		p.idx+=1
		if p.idx>count(p.sseq) then
			p.idx=1
		end		
	end
end