One of the best things about the 8-bit age was the prolific public domain scene, with many high-quality pieces of software being published in listing format in magazines.
One US publication that was particularly prolific in this regard was ANALOG (Atari Newsletter And Lots Of Games), which regularly published commercial-quality machine code programs for readers to type in, save to disk or cassette and enjoy at their leisure.
Today’s game hails from those hallowed pages. I give you Bacterion! The Plague of 2369. Nice.