Themed Issues are collections of puzzles of a specific type. You can browse the Themed Issues library by scrolling down on the game's home screen. 

Puzzles within a Themed Issue can be unlocked and played in any order.

Some Themed Issues can only be accessed when earlier ones in the same category are completed.

Some Themed Issues can only be accessed by subscribers.

Themed Issues are organized by puzzle type. Tap the cover of an Issue to view its contents in the inspection panel, then select a page to open it.

While viewing a page within a Themed Issue, you can return to the contents by tapping the icon in the top left corner of the screen.

New Themed Issues are added to the library regularly.

Themed Issues puzzles require tokens to unlock. If you're a subscriber, you will receive up to five VIP Keys each day, allowing you to play several Themed Issues puzzles without spending tokens. Once your daily keys have been exhausted you can use tokens to continue unlocking Themed Issues puzzles if you don't want to wait.