A rock big enough to end everything is headed for Earth, and Sierra hands you the job of stopping it with a two-word vocabulary. Mission Asteroid is one of the earliest Hi-Res Adventures, an illustrated text game where you type commands like GO NORTH or TAKE KEY and watch a simple picture answer back. Released as entry zero in the series because of its gentle difficulty, it works as a training ground: a straightforward countdown premise, a handful of rooms, and a parser that only understands the basics. A quaint look at where the graphic adventure began.