Pac-Man isn't exactly a new game in its own right, but a spin-off I've been engrossed in lately is Pac-Man 256. This is my commuting game of choice at the moment, mainly because of its simple gameplay and never-ending quest for higher scores.
At the base of any older game like this is a consistent desire to beat your best score. Pac-Man 256 throws some curveballs into the equation: Instead of advancing levels, you play on a never-ending board that is bound on its left and right sides but goes forward infinitely. There are different ghosts -- some move around in specific patterns, some chase you at a slow speed and some chase you at a high speed, while others blast forward at an even higher speed but only when you cross their range of vision.
It also amps up the normal power pellets that enable you to eat the ghosts. As you play, you earn new power-ups that enable you to shoot lasers, leave a fiery trail or become a bomb that kill ghosts; there are power-ups that freeze ghosts completely, make you go into "stealth mode" where no ghosts can see or harm you, or produce tiny towers that you can crush to earn more points.
This twist on a classic game isn't anything too crazy or over-the-top, but it's created an addicting game for my half-hour train rides. If you're looking for a game that can be played without using data, this is my current recommendation.