It's a nostalgia thing.
Also Numenera is a very weird concept. Every time I almost "get" it I come across information that throws all that out of a window.
It's a post apocaliptic/medival/fantasy/sci-fi ? Not calling it down but Planescape was a familiar setting and I read few good books from that world (funny story: started re-reading PS: Pages of Pain 3 days before kickstarter thingy BTW that book does Sigil and Lady JUSTICE).
Judging from the team it will be amazing, just not sure if I will like the world that much. Need a lot more new informations on the setting.