Styx

Styx was originally created by Windmill software in 1983 and released as a copy-protected, bootable 5.25" floppy disk for the IBM PC/XT.

A variation on QIX: claim the playfield by building walls and closing off smaller regions. The chief obstacle is the colorful Styx, which (fittingly) resembles a bundle of sticks, and prowls about the screen in unpredictable swirls of motion. Unlike QIX, you can draw both straight and diagonal walls; another difference is the scoring, which depends on a cycling multiplier: time your conquests right, and you may even increase your bonus tenfold.

The Styx cannot harm you as you travel along the border of your captured areas, but if it touches a wall as you build it, the wall goes down - along with you. Other ways to get yourself killed are standing still for too long (while building), and meeting the worm that crawls along the edges of your domain. Capturing at least 80% of the playfield will end the level - bonuses are awarded for more; higher levels feature faster action, more worms, multiple Styx (Stygii?), and generally nastier enemy behavior.