Simple shmup demo in Litecanvas

code.js

let scale = 2

litecanvas({
  width: 640,
  height: 480,
  autoscale: false,
})

// Art Code: 8x8/# # 6 6 6 6 # # # # 6 6 6 6 # # # # 6 6 6 6 # # 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 # # 6 6 6 6 6 6 # # 6 6 6
const ship = paint(8, 8, [
  '..6666..',
  '..6666..',
  '..6666..',
  '66666666',
  '66666666',
  '66666666',
  '666..666',
  '666..666',
], {
  scale,
})

// Art Code: 11x8/# # 9 # # # # # 9 # # # # # 9 # # # 9 # # # # # 9 9 9 9 9 9 9 # # # 9 9 # 9 9 9 # 9 9 # 9 9 9 9 9 9 9 9 9 9 9 9 # 9 9 9 9 9 9 9 # 9 9 # 9 # # # # # 9 # 9 # # # 9 9 # 9 9 # # #
const alien = paint(11, 8, [
  '..9.....9..',
  '...9...9...',
  '..9999999..',
  '.99.999.99.',
  '99999999999',
  '9.9999999.9',
  '9.9.....9.9',
  '...99.99...',
], {
  scale,
})

function init() {
  CANVAS.style.cursor='none'

  bullets = new Set()
  bulletSize = 2 * scale
  bulletSpeed = 64 * scale
  
  aliens = new Set()
  alienSpeed = 48 * scale
  
  shipY = HEIGHT*0.9
  aliensTimer = { value: 1, cooldown: 0 }
}

function tapped() {
  bullets.add(utils.vec(MOUSEX+randi(3,4),shipY))
}

function update(dt) {
  for (let b of bullets) {
    b.y -= bulletSpeed * dt
    if (b.y < 0) {
      bullets.delete(b)
    }
  }

  aliensTimer.cooldown -= dt
  if (aliensTimer.cooldown <= 0) {
    aliensTimer.cooldown += aliensTimer.value
    aliens.add(
      utils.vec(
        randi(0,WIDTH-alien.width),
        -alien.height
      )
    )
  }

  for (let a of aliens) {
    a.y += alienSpeed * dt
  }

  for (let b of bullets) {
    for (let a of aliens) {
      if (colrect(
        b.x,b.y,bulletSize,bulletSize,
        a.x,a.y,alien.width,alien.height
      )) {
        bullets.delete(b)
        aliens.delete(a)
        break
      }
    }
  }
}

function draw() {
  cls(0)
  image(MOUSEX, shipY, ship)

  for (let b of bullets) {
    rectfill(b.x, b.y, bulletSize, bulletSize, 3)
  }

  for (let a of aliens) {
    image(a.x, a.y, alien)
    // rect(a.x, a.y, alien.width, alien.height, 4)
  }
}

Demo