This is essentially a computer version of the book The Magic School Bus Lost in the Solar System and the cartoon episode "The Magic School Bus Lost in Space," except that Ms. Frizzle is lost as soon as the bus flies away from Earth. The user can fly the bus to any planet he or she chooses and play experiments and click on things there. To win the game, the user has to discover the whereabouts of the Friz. To do so they have to play a "whatsit" game to earn a token which gives them a clue as to which planet Ms. Frizzle is on. Once Ms. Frizzle is found, the bus will return to the classroom and the game begins again. You can visit all 9 planets plus the moon, however if you try to get out of the bus on Earth before Ms. Frizzle is found, Liz will say "You're giving up too soon! You still haven't found the Friz! Don't you want to keep playing?" (This game is also one of the few in the series in which Liz can talk.) When the gas giants are visited, the bus lands on one of their moons.
Source: Wikipedia, "List of video games from The Magic School Bus", available under the CC-BY-SA License.