It's amusing to me that the most modern Dr. Mario implementation for NES (it's got hard drops and ghost pieces now) will just be a minigame thrown into a platformer over a few days. Though unlike Tetris it doesn't really get the same treatment of a bunch of clones on the same platform anyway so there's no competition.
Also unlike Tetris I think it's completely legally safe as long as you avoid trademark infringement, because Nintendo actually patented Dr. Mario (instead of trying to insist game rules are copyrightable) and their patent expired.