Thief Puzzle Online is a deception game. The player must help a sneaky stickman-style thief steal from people without getting caught. When the player does well, they win up to three stars. The thief gleefully walks away with the stolen object.
The process seems simple. The character has a stretchy arm. The player must extend it over, under and around people and objects to steal things such as keys, toilet paper rolls and bone-shaped dog biscuits. Yet they face a lot of obstacles across the game's 28 levels. The game requires the player to use near-perfect timing to prevent one or more police officers or a watchdog from seeing them. An object that the thief needs to steal is often near an officer or the dog. It's typically also in a hard-to-reach location.
If the player doesn't maintain control over the thief's hand, the game automatically reveals the dropped hand and allows the guards or dog to see the thief. If the player moves the hand too close to the dog's face, they lose. They must also sometimes use a lever to access a blocked area or turn off a security system.
Thief Puzzle Online includes ad-based play. The player must watch ads to unlock different types (colors and designs) of hands and gloves. The game implies they must also watch an ad after they lose. It's important to note that this is incorrect. They can go back to the main screen that displays access to all levels to re-access the one they were playing.