Qix

Players control a marker called the Stix that moves along the edges of the playfield and draws lines across the interior, attempting to claim territory by completing enclosed regions.

The catch: a menacing entity called the Qix wanders the unclaimed space, instantly killing the player upon contact while the Stix is drawing. Additionally, Sparx enemies patrol the already-claimed borders, threatening the player if they move too slowly or linger on the lines.

The core gameplay loop revolves around risk management: slow moves (called 'slow Stix') score more points but leave the player vulnerable longer, while fast moves reduce exposure but yield lower point multipliers.

Players must claim 75% of the playfield to advance to the next level, requiring increasingly bold incursions into Qix territory as the percentage accumulates. Multiple Qix entities appear in later levels, and their unpredictable movement patterns make spatial reasoning and quick decision-making essential skills.

Qix's influence extended far beyond the arcade its territory-capture mechanic directly inspired Volfied (Taito), Gals Panic, and JezzBall (Microsoft), and echoes of it appear in modern games like Donut County and various mobile casual titles.

The game was ported to the Atari 400/800, Commodore 64, Apple II, NES, and Game Boy, accumulating a devoted following across platforms. Its elegant simplicity a ruleset explainable in seconds, mastered over years represents a high point of arcade game design philosophy from gaming's golden age.