Zanac

Zanac is the vertical shooter Compile released for the MSX in 1986, putting the player in command of the AFX-6502 Zanac craft on a twelve-level mission against the System, an entity half organic and half mechanical, bent on exterminating humanity. Its most influential feature is the ALC — Automatic Level of Difficulty Control — a dynamic difficulty system that reads the player's performance in real time and adjusts the number and aggressiveness of enemies accordingly.

That same year brought a reworked version for the Famicom Disk System, published in Japan by Pony Canyon and in North America by FCI for the NES in 1987, and months later Compile relaunched the original on the MSX2 as Zanac EX, with smoother scrolling and expanded music. Today Zanac stands as one of the most respected shooters in Compile's early catalog, a direct ancestor of the DNA the company would later perfect in Puyo Puyo.