Try it out! You can place blocks by clicking/tapping You can move usind A and D You can climb a 1 block wall by pressing the spacebar while moving in the direction of the wall! The world if infinite, but there is a clone limit of 400 on Scratch, so you can't place infinite blocks. (I could probably fix that using some advanced math, but i am too lazy to do that) You can jump 1 block gaps and you can also make a ladder by making a spiral.
Small math and creativity project :) Have fun with it!