Tetris clones

It was recently brought to my attention[1] that the bsd-games package contains 'tetris-bsd', a curses-based tetris clone. This was an oversight on my part, because if I had paid closer attention during the review I would have stripped the name 'tetris' and replaced it with something less objectionable. Now that I know, I'll do that anyway. But the bug report is claiming that all tetris clones are illegal and should be removed, not just the name 'tetris'. What is the legal status of tetris (and other game) clones? Can we get some "official" word from a legal department on what is and isn't allowed? --Wart [1]https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=238526