My 2 have really enjoyed playing with this and have spent many an afternoon outside with it (I enjoyed less having to retrieve rockets off the roof, out of tree's, neighbour's gardens etc...). You 'stomp' on an airfilled bladder which shoots the rocket up quite some distance. The harder you stomp the higher it goes. The launch mechanism allows you to set the angle the rocket flys at. The rockets are very light (lightweight plastic cylinder with a rubbery nose) and so won't break regular windows but could hurt people or do damage to a greenhouse! After a while (several months of being left outdoors to be precise) the plastic rockets go a bit brittle and break easily.