Omega Race gets my vote for underrated game of its time. It immerses you, relies on reflex gaming, is pretty fair, and there are several strategies to employ of various success rates. If you're good at it, you can play for quite some time. Try it sometime on Mame, though realize the dial control of the game doesn't translate perfectly to keyboard. It took me some time adjusting the sensitivity to have an okay time.
Another great feature of Omega Race was that you could still control the ship to a degree in attract mode if you were out of quarters. If I remember right, you could at least control the thrust and weapons fire. It was a good way to get just a little more of your fix even if you were broke but still not ready to go home.
Oh, and amazingly, I found that the best home port ever for Omega Race was on the Commodore VIC-20 (need to see about getting Omega Chase Deluxe for my Vectrex to see how it compares). That was one of the most faithful renditions ever of the arcade version. And back when I was a big time classic video games collector, I discovered the best controller to use with it was the Starplex. Back when I had time to have my systems set up, that I totally kicked ass on Omega Race and several other games with that controller.