Jumpar.io is a game about jumping. Who could've guessed? You play as a squishy blob, and you are able to hop around the map. To attack other players, you must jump from a tall height and land on top of them. This will cause them to pop, and their mass to shoot out in all directions.
Use your W, A, S, and D keys to move and jump around. You can tap W or Spacebar multiple times to double jump.
Always try to stay higher in elevation than other players. This makes it so that they cannot easily destroy you, but you can easily land on them.