Tap on a stack: You select a stack by tapping it.
Connect with other stacks of the same color: Once you select a stack, you try to link it to other stacks of the same color to form a longer chain.
Form stacks / chains of 10 or more: One of the objectives is to make long stacks (length ≥ 10). Bigger stacks give more “score” / help you meet level-goals.
Watch your moves: You have limited moves or constraints per level; you must achieve the objective before you run out of moves, or before you run out of opportunity.
Progress through levels: Levels get harder as you go, likely adding complications (more colors, tricky board layouts, etc.).