Bloxorz Cheat Level 3 -

: You need to flip the block horizontally to fit through the single-tile bridge.

If you need to jump to other early levels, here are the official codes from sources like Newsweek : Cheat Code 02 03 918660 04 05 06 07 08 09 10 Bloxorz Cheat Level 3

: Move right until you reach the middle section. : You need to flip the block horizontally