Tontie is a fun and free internet game. And it is the game of the week. As the site describes it "this is kind of an evolved whack-a-mole game". Instructions at each level tell you what to hit and what not to hit. Each level adds a little difficulty. Accumulate gold coins to purchase a bigger mallet or more lives.
You use your number pad for controls. Click the number that corresponds with wear the tontie appears. This game takes reflexes but also an understanding of the pictogram. When the Store appears whack it to get inside to purchase upgrades.
If you don't need lives, I suggest upgrading your hammer as soon as possible.