Yes I have and don't lie. The steam logo should be enough to tell anyone that what you're buying is an "all access pass to the steam service". Further than that, might I direct your attention here http://universesandbox.com/faq/#purchase specifically this paragraph https://archive.is/aKZD7#selection-1333.0-1347.254 where they quite clearly say steam is required and that they haven't decided whether it will be drm free at some point.