Tower Ball is a combination of tower defense with incremental leveling. The bars on the top left lead to other pages. 
Tips 
    You can swipe up or down on the screen to quickly change levels
    The game saves automatically, however you can save manually in the settings
    Game running slow? Adjust your performances settings using the performance button in the settings.
    The in game reset only resets the upgrade points. Dark Powers & Gem Upgrades are not affected. You get back all the upgrade points you spent, plus any pending upgrade points.