Two modes: guess the meaning, or break a character into its parts.
Chinese characters are built from smaller components called radicals. In Meaning mode you guess a character's English sense; in Components mode you break a character into its parts. Both modes train the single most useful habit for learners: seeing characters as combinations, not random shapes.
New to radicals? Start with our Guide to Chinese Radicals, then practise stroke order in the Stroke Order game.
What is a radical? A radical is a recurring component that often hints at a character's meaning or sound.
Which mode should I pick? Beginners start with Meaning; Components is great once you recognise a few hundred characters.
Is this free? Yes — Hanzi Play is free and needs no account.