Smack A Thief! is an mini-game from the Settlers-series, intended as an advertisement game for the - at the time - upcoming The Settlers: Fourth Edition.
Your mission is to protect your gold and silver from the thieves. You have a few guards available, who protect your treasure, but they seem that they don't have slept well at night, so they doing it now at work, mostly when the thieves are carrying away your treasure. So you have to wake your guards by punching them, they then trying to stop the thieves, when they are in range. But you can also punch the thieves directly, either way, they let the gold/silver fall down and run away. Your settlers will then return the treasure back to the depot. The harder you punch the thieves, the more time you have, before this one returns.
For your task, you have some gimmicks available (you can find them in some levels), like bombs, which will destroy the terrain and throw all people in range away, matchsticks, to set them on fire, or an air pump, to inflate them.
Each level has a time limit, so all you have to do, is to stand with some of your treasure until the time runs out. If all of the gold/silver has been carried away, you loose.
The game offers an online high score. To get in there, you must stop manually before a new level (or finish the complete game). If you loose in a level, your score is lost.