Help the Elwins to rebuild their city! Build bridges so that they can cross the streams safely. You can use many kind of materials, with different properties: the bridge paths are good to walk; the steel ones (2 parallel lines) are strong, but they are expensive; the rope is cheap but is not too strong. You also have to consider money: as you advance you earn it, and you can use it to buy new parts and materials, but if you run out of money the Elwins will not be able to continue building and you lose the game.
To build a bridge, click at a point to start, then move to draw a line to the final track; don't forget that there's a size limit for each bridge track! If you want to eliminate 1, place yourself on it and click. To remove many tracks, click the points that are connecting them. Click the background and drag to move through the level scene, that is too big to be fully visible at screen. To zoom use the + and - buttons. You also have other buttons like UNDO and RESET (with obvious functions). After you prepared the bridge, click the START button: the Elwins will try to cross it and if they are able to do it, you pass to the next level.