AWESOME!

If you go to: SteamApps\common\Geometry Dash\Resources you'll find a PNG file called GJ_GameSheet02-uhd. Here you can see all the cubes and a bit more. Just remove a cube and you've now got your invisible cube. To go full extreme you gotta find the square.png and make it transparent. This removes the particle effects, this is the reason you don't see the white squares where I land or where I "walk". Next thing you wanna do is to find the streak_01_001.png and make it transparent. This is the little trail your ship makes. Now you're invisible, the extreme way.

How are you invisible though?

I'm working on it, don't worry!

now do it on level 18 - Theory of everything 2

Haha, thank you.

you are so pro