Tron game built for the PICO8 fantasy console

tron.lua

pico-8 cartridge // http://www.pico-8.com
version 16
__lua__
line_weight = 1
border_colour = 7

up = 2
right = 1
down = 3
left = 0

ply1 = {}
ply1.x = 96
ply1.y = 64
ply1.colour = 12
ply1.name = "blue"
ply1.dir = up
ply1.num = 0
ply1.lost = false
ply1.score = 0

ply2 = {}
ply2.x = 32
ply2.y = 64
ply2.colour = 8
ply2.name = "red"
ply2.dir = up
ply2.num = 1
ply2.lost = false
ply2.score = 0


function _init()
	cls()
	rect(
		0, 0, 127, 127, border_colour)
end

function another_game()
	cls()
	rect(
		0, 0, 127, 127, border_colour)
		
	ply1.lost = false
	ply1.x = 96
 ply1.y = 64
 ply1.dir = up
 
	ply2.lost = false
	ply2.x = 32
 ply2.y = 64
 ply2.dir = up
end

menuitem(
	1, 
	"another game", 
	another_game
)

function _update()
 if is_game_active() then
  update_dir(ply1)
  update_dir(ply2)
  move(ply1)
  move(ply2)
  collision(ply1)
  collision(ply2)
  increment_score()
	end
end

function _draw()
 rectfill(
 	0, 0, 127, 12, border_colour)
	print(
		" red: " .. ply2.score, 
		1, 1, ply2.colour
		)
	print(
	 "blue: " .. ply1.score, 
	 1, 7, ply1.colour
	)
	if is_game_active() then
 	head(ply1)
 	head(ply2)
 else
		winner = get_winner()
		print(winner.name .. " wins", 44, 74, winner.colour)
 end
end

function head(ply)
	rectfill(
	 ply.x, 
	 ply.y, 
	 ply.x,
	 ply.y,
	 ply.colour
	)
end

function move(ply)
	if ply.dir == up then
		ply.y -= line_weight
	elseif ply.dir == right then
		ply.x += line_weight
	elseif ply.dir == down then
		ply.y += line_weight
	elseif ply.dir == left then
		ply.x -= line_weight
	end
end

function update_dir(ply)
	prev_dir = ply.dir
	if btnp(up, ply.num) and prev_dir ~= down then
		ply.dir = up
	elseif btnp(right, ply.num) and prev_dir ~= left then
		ply.dir = right
	elseif btnp(down, ply.num) and prev_dir ~= up then
		ply.dir = down
 elseif btnp(left, ply.num) and prev_dir ~= right then
 	ply.dir = left
	end
end

function collision(ply)
	coord = pget(ply.x, ply.y)
 if coord == ply1.colour or coord == ply2.colour or coord == border_colour then
   ply.lost = true
 end
end

function is_game_active() 
	if ply1.lost or ply2.lost then
		return false
	else
		return true
	end
end

function get_winner()
	if ply1.lost then
		return ply2
	else
		return ply1
	end
end

function increment_score()
	if ply1.lost then
		ply2.score += 1
	elseif ply2.lost then
		ply1.score += 1
	end
end

http://tron.neillyons.io/