If you like playing casual games, you will love Balloon Wars or Orb Wars. This popular game lets you use orbs to fight against other players. You must connect three or more orbs of the same color to defeat the other player. You can play the game for free, or you can purchase in-app purchases.
Orb Wars is a two-player deathmatch game where players use orbs to blast each other until one of them dies. You don't have as many options as in other games, but you have two attacks and several different levels to choose from. Some levels have objectives, such as reaching the end first, but most levels are deathmatches between two players.