A Monolith Maze Thing
You can get to the to the top of this structure by keeping an eye on the green blocks. If climbing gets tedious, press F to toggle flight. To redo the Monolith generation, press R. You may have to click the game window so that it doesn't stop tracking the mouse when its outside the window.
First, I generate cubes randomly within a large box, the probability of cubes spawning decreased the closer it was to the edges of the box.
Next, a sphere goes around, inside the Monolith kind of randomly. It'll tend to go upwards more than downwards and it'll never go up twice in a row. As it goes, it deletes any blocks in its path and lays down blocks below as needed (those are the green cubes), making sure that it doesn't accidentally block your way up in the process.
So it's kind of a weird maze thing with a path to the top.