The object of the game is to collect the Goal items (shown on the top of the screen), within a certain number of Moves (shown in the top left of the screen). Early in the game those goals are usually a specific color of dots (collect 20 red dots and 20 blue dots). Later in the game you will also need to complete new objectives, such as breaking ice tiles or extinguishing fire dots. As you progress through the game you'll discover amazing new environments and challenging & satisfying new game mechanics. We hope you stick with it!
If you're confused about any particular mechanic, there's lots of help available in the Mechanic Tutorials section, or feel free to write us at td-help@weplaydots.com. We're always happy to help!