Okay, let's see if I can describe this:
It's a cross between Sim City and Tetris.
You get an empty city grid, blocked by streets and such, where you have to "build" buildings and houses. The grid is of course made of 1 block squares. On the touch screen, you "draw" what tetris block you want to put down to build by click the shape into the grid. The various shapes you can use show up on the bottom like the next piece in Tetris, except you can usually always choose between 4 different shapes.
It's 100% touchscreen and pretty easy, but I can see it getting more difficult in the later levels if they add a sharp time limit or you have to build bigger buildings.
Did this description make sense at all?
Edit: Oh, as you progress, the game starts to require you use ONLY certain color blocks for some buildings, to dictate what kind of building they would be (like SimCity), so I can see the challenging puzzle aspect coming from that.