Basic Pico-8 Game

Basic_Game.lua

in_progress = 0
start_end_game = 1
game_over = 2

left=0 right=1 up=2 down=3
valid_moves = {left,right,up,down}

function _init()
 player = {}
 player.x = flr(rnd(120))
 player.y = flr(rnd(114)+8)
 player.startsprite = 0
 player.endsprite = 1
 player.sprite = 0
 player.speed = 2
 player.stuck = 0

 enemy = {}
 enemy.x = flr(rnd(120))
 enemy.y = flr(rnd(114)+8)
 enemy.startsprite = 4
 enemy.endsprite = 5
 enemy.sprite = 4
 enemy.speed = 1
 enemy.stuck = 0

 state = in_progress
 score = 0
end

function move(unit)
 unit.sprite += 1
 if unit.sprite > unit.endsprite then
  unit.sprite = unit.startsprite
 end
end

function draw_unit(unit) spr(unit.sprite, unit.x, unit.y) end
function get_map_cell(unit) return mget(flr((unit.x+4)/8), flr((unit.y-4)/8)) end

function hit_house(unit) return get_map_cell(unit) == 16 end

function move_unit(unit, direction)
 unit.moving = false
 
 if hit_house(unit) then
  unit.stuck += 1
  if unit.stuck > 4 then
   unit.stuck = 0
  else
   return 
  end
 end
 
 if direction == left and
    unit.x - unit.speed > 0 then
     unit.x -= unit.speed
     unit.moving = true
 end
 if direction == right and
    unit.x + unit.speed < 120 then
     unit.x += unit.speed
     unit.moving = true
 end
 if direction == up and
    unit.y - unit.speed > 8 then
     unit.y -= unit.speed
     unit.moving = true
 end
 if direction == down and
    unit.y + unit.speed < 120 then
     unit.y += unit.speed
     unit.moving = true
 end
 if not unit.moving then
  unit.sprite = unit.startsprite
 else
  move(unit)
 end
end

function move_player()
 for i=1,#valid_moves do 
  if btn(valid_moves[i]) then
   move_unit(player, valid_moves[i])
  end
 end
end

function move_enemy()
 if enemy.x > player.x then
  move_unit(enemy, left)
 end
 if enemy.x < player.x then
  move_unit(enemy, right)
 end
 if enemy.y > player.y then
  move_unit(enemy, up)
 end
 if enemy.y < player.y then
  move_unit(enemy, down)
 end
 enemy.speed += 0.0005
end

function distance(p0, p1)
 dx=p0.x-p1.x dy=p0.y-p1.y
 return sqrt(dx*dx+dy*dy)
end

function check_game_over()
 if 
  distance(enemy,player) < 7 
  and state != game_over 
   then
    state = start_end_game
 end
end

function _update()
 move_player()
 move_enemy()
 check_game_over()
end

function _draw()
 cls()
 if state == in_progress then
  map(0,0,0,8,16,15)
  draw_unit(player)
  draw_unit(enemy)
  score += 1
  print("score: "..score)
 elseif state == start_end_game then
  sfx(0)
  state = game_over
 elseif state == game_over then
  print("\135 game over \135")
  print("your final score was: "..score)
  print("press action to try again")
  if btn(4) then 
   _init() 
  end
 end
end

Best of luck with it! It's a fantastic engine and a great place to start