This is a fairly simple side scroll engine. Feel free to use it or leave suggestions. Use the arrow keys to move the zombie. Here is my game based off this engine: https://scratch.mit.edu/projects/32297558
I adapted @griffpatch_tutor 's amazing platformer tutorial: https://scratch.mit.edu/projects/67727504/ to work as a side scroll engine. Please see his project for a much more detailed explanation of all of the pieces. Feel free to use.