Cray 5

Set on board a colony ship destined to populate new worlds in the far reaches of the galaxy, your mission comes to an abrupt stop when one of the craft’s reactors is hit by an asteroid - causing a massive radiation leak and damaging the ship's main computer, the Cray-5 (this kind of thing always happens to me, natch). The damaged computer has initiated the ship's self-destruct sequence (why would a colony ship even have one of these?), so IT IS UP TO YOU™ to save yourself, your fellow colonists and indeed humankind by safely shutting the thing down.