If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Cranes are incredible vehicles that can pick up insanely heavy stuff. You now have the opportunity to check out for yourself all the possibilities, by constructing some amazing things: a train, a spaceship, a ship, a house, a stadium, a roller coaster, a bridge or a heavier crane. Just look around the map and find all the items and bring them together. Be fast so you can finish before the time runs out, but also be careful not to damage your crane. Have a lot of fun!