Use the arrow keys to move, Press the down arrow to crouch, fall when wall sliding, fall through jump though platformers, or press the down arrow and the right or left arrow keys to slide. Collect keys to open the locked doors. Don't touch spikes or enemies or you will restart at the beginning, or the check points you collected.
I am sorry to say that multiplayer will not work in scratch it will work in turbowarp only. When if you have scartch addons extension you need to able a option name is Cloud games this option is will anble a option to type a project oe studio type any multiplayer game URL.