You walk into a giant cave, floored with clouds. There is a single golden platform, floating in the sky near the precipice you stand on, like a boat docked on the shore. Engraved on it is the arcane rune XIII. A short distance further you see your destination: another platform extending out into the clouds.
The platform is large enough for all of you and supports your weight. On it you find nearly two dozen glass bottles, each appears to hold in it a cloud, and each bears a different arcane rune, I-XI. XIII is notable absent. Upon unstoppering the last bottle, a cloud in the shape of the rune appears, and a fine silver thread attaches it to the golden platform which begins to shift. Upon opening another, "XIV", it too has a similar effect. You wait for the room to stop shifting.
Unfortunately you're further from your goal, and only the golden platform XIII can support your weight. Placing the stoppers back on the bottles, however, sucks their ethereal clouds back in, leaving the room once again how you found it. You have an idea, though, and upon unstoppering bottles "I" and "II", you've made it slightly closer to the other side.
After just two more opened bottles, the platform on which you stand has gotten close enough to the stone pier for you to safely jump across.
You continue on your epic quest, more glad than ever that you decided not to study computer science...