Of interest to me regarding Roblox is that it's been around for a long time - public release in 2006, almost 20 years ago! It was around when I was a kid, and I vaguely remember being aware of it and thinking it was dumb (certainly, I didn't know anyone who played it).

I wonder what happened to make it so popular in the present day. Was it incremental improvement, or a better fit with modern devices/culture; maybe simply being free to play?

What made it so popular was a combination of it being cross platform as well as turning into a "game/experience platform" instead of just a game.

But it is legitimately incredible what some people created in it. I remember playing a very good/accurate counter strike source clone in roblox. Felt exactly like playing a source engine game. I doubt that it was made by a kid.