That is Citadel [0], not Citadel BBS [1], but related.<p>[0] <a href="https://en.wikipedia.org/wiki/Citadel/UX" rel="nofollow">https://en.wikipedia.org/wiki/Citadel/UX</a><p>[1] <a href="https://en.wikipedia.org/wiki/Citadel_(software)" rel="nofollow">https://en.wikipedia.org/wiki/Citadel_(software)</a>