The Mutanoid Math Challenge

The Mutanoid Math Challenge is an early-1990s edutainment title, part of the small "Mutanoid" family of learning games that dressed up drill-style exercises in a cartoonish sci-fi wrapper of mutant creatures. Like most software of its type from that period, it was aimed at classrooms and home learning rather than the arcade or adventure crowd, pairing arithmetic practice with light competitive play.

I don't want to overstate the specifics of its rules, since detailed documentation of this exact release is thin. What's clear is the era it belongs to: the wave of PC edutainment that tried to make numbers palatable to kids weaned on games. As a historical artifact of that movement it's more interesting than it is as something to actually sit down and play today.