Tokens can be purchased from the in-game store (which can be quickly accessed by tapping the ‘token’ counter in the status bar area).

Tokens are also awarded every day the game is played. The daily reward can be claimed by completing a puzzle on that day - if no puzzles are currently unlocked and you don't have enough tokens to unlock any further puzzles in the current chapter, one puzzle will be unlocked automatically.

You may also be awarded tokens for completing puzzles and other objectives in the game.

You may also be able to earn additional tokens by viewing video ads or taking advantage of Tapjoy offers in the Tokens section of the Store (these options may not always be available).