How can I add backface culling, beter resizable shapes, like circles and collision with objects or other hitboxes that aren't visable.

https://en.scratch-wiki.info/wiki/Hitbox

A hitbox is usually a box or a rectangle that is black in colour, with the transparency set to 100. When the sprite is touching the colour black or the hitbox itself, it will initiate the script that stops it from moving.