Retro Game of the Day! Volfied
Volfied (or "Ultimate Qix," but really, which name would you prefer?) by Taito, arcade release in 1989 and ported shortly after to Sega Genesis, PC-Engine, and other platforms.
A game nearly lost to time, Qix was part of a very old generation of videogames where graphics were as simplistic as could be, and gameplay was the only leg to stand on. With it's unique "fill the entire screen by line-drawing boxes," Qix stood quite apart from the rest and enjoyed some popularity for it.
The game is still as enjoyable now as it was when it first appeared, but its looks never made it an easy one to sell. With its' legacy, a bevy of sequels followed (some official, most softcore-porn-themed knockoffs) although Volfied was the only "true" follow-up.
Volfied expanded on the original by sticking to what worked, and not trying to complicate things. The super-simple source material was given an appropriate sci-fi facelift, and gameplay was augmented with extra challenge. The game was interesting in that it improved on the original, and yet the two are able to coexist (it wouldn't be fair to say that Volfied is "better" than Qix...)