I haven't played most of the Multimorphic titles.
I've never played Baywatch, Skateball, Monopoly, Wheel of Fortune, Bugs Bunny's Birthday Ball, Rocky, Hoops, Car Hop, or Title Fight
There's a number of ultra rare games I haven't played (Krull, King Kong, Loch Ness Monster, Qbert's Quest, Goin Nuts, Kingpin, Pinball Circus, etc) and rare foreign games I haven't touched either.
There's a lot of games I've only had the opportunity to play once or twice, which was barely enough to get a good feel for them.
There's a lot of EM games that I haven't played, but I don't really seek them out a lot of the time, though I do have some favorites from that era.