Kettle is a short puzzle game based around the idea of police containment of protesters. Given a number of people in the centre of the grid, you move the border so as to position all the people in the grey block.

Your police need to be moved in a specific way on each level so that the protesters will fit into the space and not bump into each other, and sometimes you can get completely stuck and need to press space to reset the puzzle. It's pretty clever, although each level is short and can usually be completed through trial and error.

Go play this politically-motivated puzzler over at Stephen's site.