Before reading this post, please first read this one: http://forums.dirtybomb.nexon.net/discussion/15601/game-bug-infinite-wall-jump
I use the bug shown in that post to do this skybox glitch.
Details: Using infinite high jump glitch allows players get on top of many buildings in Trainyard. Players can still attack when they are above those buildings.
Prove: http://imgur.com/a/9zN2Q
Please PM me to see how I do this glitch, I won’t publish it here because its totally OP.