I have capitalized key ideas in the instructions. Please read them all so you know how this works. INSTRUCTIONS: click a block to add it. they should be self explanatory, however the LOOK LIKE block (in this case) acts as the NEXT COSTUME block. click the M,L,C buttons to switch categories. CONTROL BLOCKS ARE NOT EXECUTABLE EXCEPT THE WAVE FLAG block. Click the buttons under "EDIT SCRIPT" to change the script you are editing. Click the GO BUTTON ON THE STAGE to run. SCRIPTS WILL RESTART WHEN STARTED BEFORE FINISHING. HOW TO LOOP: At the end of a "when flag waves" script, add the "wave flag" command.
All by me. This is a simulation of Scratch 0.1! DISCLAIMER: Scratch 0.1 had more capabilities, such as importing pictures and videos, as well as creating multiple sprites. The show and hide blocks may or may not have existed since "no sprite" is default in the look like block. SOURCE: Scratch Wiki Image