Yeah the post was getting a bit long, there are a bunch of similar games to the ones listed, I just used one of each to exemplify each strategy.

Core is very similar to Roblox in that the creation tools are rather involved, it tends more to a platform with distinct creator/consumer roles.

There's also the PS4 game Dreams, as well as other integrated-modding initiatives like in Krunker.

It's a Roblox copy, and as such is already mentioned.