The million years / alien audience makes me think an EM would be the way to go. At that point, the audience is so far removed from how we think about pinball that the differences between TZ or MM are irrelevant. For that audience, I think you want something to put forth the essence of what the game of pinball is about in the simplest most understandable format possible and that's an EM. As which game specifically, I'm partial to Card Whiz but I don't think it will matter much to aliens a million years from now.

If we're just putting a pin in a time capsule for 100 years 'Dialed In' would be perfect. It's a good game and there's no licensed theme to confuse people. They'll find the references to cell phones, drones, etc... hilariously dated and it will make for an excellent museum piece.