This is block physics playground but when it was first created if you want to see the real deal click this link: https://scratch.mit.edu/projects/775234536/
Press space to spawn the blocks. Press d while touching a block to delete that block. Press m to delete all of the blocks. You can drag the blocks. Also, if you press R or B you get blocks that noclip into each other. Press P to return it. If you spawn too much it lags scratch.