Quantum Space Invasion
The strange properties of this bacteria, occasionally brought down to Earth by a NASA space mission, are caused by its ability to exist in the quirky world of quantum mechanics, not obeying the laws of normal physics. It is smaller than a nano-machine and just slightly bigger than an atom, allowing it to interact with particles, molecules, and cells on a fundamental level. This bacterial species is a very efficient life eradicator, with almost absolute lethality, explosive spread rates and resistance to normal medical cure.
Will the humanity’s best efforts be enough to stop this weird disease? Or will they fail like everyone, well, before them? (There are two win conditions).
(Disclaimer: the author really sucks at physics and this was made just for fun, no education intended. Do not report factual errors in the descriptions.)