HTMLify

*, *:after, *:before {
  box-sizing: border-box;
}

body {
  margin: 0;
}

.game-wrapper {
  width: 100%;
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.game-container {
  flex: 1;
  background: url("https://bhckids.org/wp-content/uploads/2015/04/background.jpg") no-repeat;
  background-size: cover;
  background-position: center center;
  display: flex;
  width: 100%;
  justify-content: center;
  position: relative;
  z-index: 500;
}
.game-container:after {
  content: "";
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  height: 100%;
  border-left: 2px dashed #555;
}

.game-col {
  flex: 1;
  display: flex;
  align-items: flex-end;
  max-width: 600px;
}

.computer-col {
  transform: rotateY(180deg);
  max-width: 600px;
}
.computer-col .cannon {
  transition: 1s ease-in;
}
.computer-col .cannon .pipe {
  transition: 1s ease-in;
}
.computer-col .cannon .wheel {
  transition: 1s ease-in;
}

.cannon {
  position: relative;
  z-index: 100;
  transform: translateX(5cm);
}
.cannon:before {
  content: "";
  z-index: 5;
  position: absolute;
  height: 200px;
  border-right: 1px dashed #fff;
  left: 131px;
  top: 50%;
  border-radius: 50%;
  transform: translateY(-50%);
}
.cannon .pipe {
  width: 160px;
  height: 40px;
  margin-bottom: 50px;
  background: linear-gradient(to right, #333 1%, #333 35%, #222 36%, #222 36%, #222 41%, #333 41%, #333 100%);
  border-radius: 0 50px 50px 0;
  position: relative;
  transform-origin: right center;
}
.cannon .pipe:after {
  content: "";
  position: absolute;
  width: 15px;
  height: 50px;
  background: #222;
  border: 2px solid #333;
  border-radius: 50px;
  top: 50%;
  transform: translateY(-50%);
}
.cannon .pipe:before {
  content: "";
  position: absolute;
  width: 120px;
  height: 60px;
  background: linear-gradient(to right, #333 1%, #333 35%, #222 36%, #222 36%, #222 41%, #333 41%, #333 100%);
  border-radius: 50% 50px 50px 50%;
  top: 50%;
  transform: translateY(-50%);
  left: 50%;
}
.cannon .wheel {
  position: absolute;
  width: 100px;
  height: 100px;
  color: #222;
  border: 10px solid currentColor;
  border-radius: 50%;
  bottom: 0;
  right: -21px;
  background: linear-gradient(to bottom, #752f16 93%, #1c0701 94%);
  background-size: 100% 10px;
}
.cannon .wheel:after {
  content: "";
  position: absolute;
  width: 35px;
  background: #111;
  height: 35px;
  left: 50%;
  top: 50%;
  border-radius: 50%;
  transform: translate(-50%, -50%);
}

.level {
  width: 60vw;
  position: absolute;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
}

.ball {
  width: 30px;
  height: 30px;
  background: #333;
  border-radius: 50%;
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  left: 0;
}
.ball:after {
  content: "";
  position: absolute;
  width: 100%;
  height: 100%;
  background: #333;
  border-radius: 50%;
  left: 0;
  top: 0;
}

.cm .ball:before {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -40%);
  width: 300px;
  height: 250px;
  background: url(https://www.onlygfx.com/wp-content/uploads/2017/06/comic-boom-explosion-2-1.png) no-repeat;
  background-size: 100% auto;
  z-index: -1;
  opacity: 0;
}

.fire {
  -webkit-animation: fire 0.3s ease-in-out;
          animation: fire 0.3s ease-in-out;
}

.defended .fire .ball:before {
  transition: 0.2s 0.3s linear;
  opacity: 1;
}

.wheel-handle {
  position: absolute;
  background: #fff url("https://cdn.onlinewebfonts.com/svg/img_520243.png") no-repeat;
  background-size: 100% auto;
  background-position: center;
  width: 40px;
  height: 40px;
  left: 111px;
  top: 19px;
  border-radius: 50%;
  z-index: 10;
  cursor: w-resize;
  opacity: 0.8;
}

.level-handle {
  position: absolute;
  background: #6200EA;
  width: 40px;
  height: 40px;
  left: 140%;
  top: 50%;
  border-radius: 50%;
  transform: translateY(-50%);
  z-index: 54;
  color: #fff;
  text-align: center;
  line-height: 36px;
  -webkit-user-select: none;
     -moz-user-select: none;
      -ms-user-select: none;
          user-select: none;
  cursor: -webkit-grab;
  cursor: grab;
  border: 2px solid #fff;
}
.level-handle:after, .level-handle:before {
  content: "";
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  border: 10px solid transparent;
  border-bottom-color: #fff;
  top: -27px;
}
.level-handle:after {
  border: 10px solid transparent;
  border-top-color: #fff;
  top: 44px;
}
.level-handle:active, .level-handle:focus {
  cursor: -webkit-grabbing;
  cursor: grabbing;
}

.level-monitor {
  position: absolute;
  background: #fff;
  width: 40px;
  height: 40px;
  left: 130%;
  top: 50%;
  border-radius: 50%;
  transform: translateY(-50%) rotateY(180deg);
  z-index: 54;
  color: #333;
  text-align: center;
  line-height: 36px;
  -webkit-user-select: none;
     -moz-user-select: none;
      -ms-user-select: none;
          user-select: none;
  border: 2px dashed #777;
}

.countdown {
  position: fixed;
  z-index: 5000;
  width: 100px;
  height: 100px;
  background: #fff;
  color: #00897B;
  font-size: 30px;
  font-family: arial;
  top: 10px;
  left: 50%;
  transform: translateX(-50%);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 10px solid #00897B;
}

.road {
  background: #E9B7A4;
  height: 100px;
  position: relative;
}

.scale {
  display: flex;
  position: absolute;
  left: 50%;
  top: 2px;
  transform: translateX(-50%);
  -webkit-user-select: none;
     -moz-user-select: none;
      -ms-user-select: none;
          user-select: none;
}

.scale-point {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
}
.scale-point.mirror {
  flex-direction: row-reverse;
}
.scale-point li {
  width: 1cm;
  position: relative;
  padding-top: 20px;
}
.scale-point li .unit {
  display: inline-block;
  position: relative;
  transform: translateX(-50%);
}
.scale-point li:before, .scale-point li:after {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 1px;
  height: 17px;
  background: #000;
  transform: translateX(-50%);
}
.scale-point li:after {
  left: 50%;
  height: 12px;
  color: #555;
  box-shadow: 0.1cm 0, 0.2cm 0, 0.3cm 0, 0.4cm 0, -0.1cm 0, -0.2cm 0, -0.3cm 0, -0.4cm 0, 0.1cm 0, 0.2cm 0, 0.3cm 0, 0 2px #000;
}

@-webkit-keyframes fire {
  50% {
    left: 5px;
  }
}

@keyframes fire {
  50% {
    left: 5px;
  }
}