Castle on the Coast (UP)

Ok i just did it.And here's what i had to do:

At the main menu,go to Settings -> Arcade mode -> Any time -> Start

Now,grab the Jetpack in front of you and try to hit the ceiling by walljumping and using the jetpack.Once you hit the invisible wall on the ceiling,the achievement should unlock.
Well,that's how i unlocked it.

And here's a video if you need a visual help:

Hope it helps :)

Impossible to get because you can't pass through the invisible walls on Xbox.

Here's the reply i got from the devs:

"Weird story, its a PC only version achievement. You normally get it by going to settings and unchecking "invisible walls". Because exploring out of bounds makes the game messy, we were concerned about not passing xbox certification (approval to ship on their console)"

I'll update my guide when i'll have more news.