Does Dwarf Fortress count? It may turn out to be just one lifetime of work, but what appeals to me romantically about that crazy product, is that (until recently anyway) it was never in any rush to appear complete, and one could imagine a future, like a software Sagrata Familia, that it could survive it’s original crazy/genius architech and people could pick up the torch and continue to add even more baroque and unfathomable complexity for at least another century or two.