It's as barebones as it gets; essentially a straight port of the original Game & Watch game without the enhancements found in the Game & Watch Gallery series. I have no idea how this game kept me enthralled as a kid, guess I was easily entertained.
Wow, not very good, but I guess I shouldn't be too surprised. I think I got it for less than a buck on the eShop back in the day, though, so that's nice.