I was originally just going to make a simple tank for my own use, and not upload it to phunbox, but it grew from there, and now it is something that I like to think of as quite extraordinary. I may be biased though
Let me make this clear. This is not meant to be beautiful, it is meant to show off the machine that I made.
The main idea of it is that it will climb vertical walls that are much taller than the vehicle's original length.
It extends from about 10m to 15m, which is 1.5 times it's starting length.
Arrow keys to control the front track, c,x,z to control the rear track, and lastly shift to extend, and / shrink.
P.S. the stairs are really tough. I will be impressed if you can do it on your first try. Also, it sometimes steps out of it's tracks,

so remember to pause and resume often.
Edit: Some may think that it is cheating to have things move through the ground, but I don't think so, and I still put a lot of work into fine tuning, and building it, so even if it is cheating I put a lot of work into it