*{
   padding: 0;
   margin: 0;
 }
 #game{
   width: 500px;
   height: 200px;
   border: 1px solid black;
 }
 #character{
   width: 20px;
   height: 50px;
   background-color: red;
   position: relative;
   top: 150px;
 }
  .animate{
   animation: jump 500ms;
 }
 @keyframes jump{
 0%{top: 150px;}
 30%{top: 100px;}
 70%{top: 100px}
 100%{top: 150px}
 }
 #block{
   width: 20px;
   height: 20px;
   background-color: blue;
   position: relative;
   top: 130px;
   left: 480px;
   animation: block 1s infinite linear;
 }
 @keyframes block{
   0%{left:480px;}
   100%{left:-40px;}
 }