I would say "inspired by". They built on the concepts presented by their predecessors and turned them into something better. It's the same pattern all art goes through. Everything is in some way built on the shoulders of previous giants.
Yeah, that's how I viewed Rising World and shall always view it that you simply take someone's concept and improve on it. That's how we're improving on computer parts, cars, planes, and etc in the world that without someone else putting their own spin we wouldn't be where we are now in a global sense, as well as Rising World. Someone is going to look at Rising World in the future to hopefully 1-up on that.
On a similar note UBOAT is to Silent Hunter 3 what Rising World is to Minecraft, an improvement; A step up in the ladder.