James Clear's marketing headline for Atoms "Tiny changes, remarkable results." works well and stands out in a crowded space. Here's why it works:

• It directly echoes the core philosophy from his bestselling book "Atomic Habits" that has sold more than 20 million copies

• Creates a compelling contrast between "tiny" and "remarkable" to highlight the power of small habits

• The italics draw visual attention to the key terms and reinforce the emphasis

• The simple, balanced structure (two words, two words) makes it highly memorable and quotable

• Communicates the app's purpose (habit tracking for incremental improvement) without explicitly stating it

• Promises significant outcomes from manageable actions which helps make behavior change feel accessible