Nimtrix solution seems to work.
I tried a solution with car behavior that works but you could not associate it with a bullet movement to "move" the background as Nimtrix do. And the movement seems to be "not real".Here the sample
I work to another solution based on samples i found on forum.
That's the result.
I think is the best solution: infinite background scrolling with two images (with Nimtrix solution you have to put a very long background) - no bullet behavior - 8direction(up-down) on object to move - the movement seems to be more "real". Hope you enjoy it.
(Use up - down arrows to move)Here the second sampleDado2012-03-27 20:03:07