Roblox (talking in past tense; not sure how much of this is still true) allowed you to create "Places", which were basically 3D interactive universes that consisted of a few primitive parts (rect. prisms, cylinders, etc.) arranged and connected to each other, as larger solid objects, or with hinges. It was, in other words, a multi-player physics sanbox. Also, the use of the word "place" instead of "game" is interesting to note; as a child, it felt like they could really be anything, with no particular expectations.
I don't remember when Lua scripting was added - I think it was around 2008-2009 or somethng - but it allowed you to perform simple event-based programming, registering clicks/deaths/collisions/etc and manipulating the game world. As a child I saw this as a form of magic. What would otherwise be a physics sandbox with inanimate objects interacting in a strictly mechanistic fashion became one in which anything could happen. You know, magic. Maybe that sounds stupid, but that was my thinking.
So I became a programmer because I wanted to be a wizard. I am still pursuing this goal. Also, RIP Erik Cassel. His tutorials were one of my first - if not my first - introduction to programming ever. He died too soon.