The Sample Game we shall be developing together is whimsically called The Quest of the Golden Banana. There is nothing stunningly original in its design, and it will probably strike you as Dr Who meets the Lord of the Rings with a hint of old-fashioned text adventures like Zork thrown in for good measure. For our purposes, however, its contrived nature is an advantage, since it allows us to set up of sorts of implausible situations and puzzles that can put the TADS 3 library through its paces.
To give a brief summary of the game (which you might want to try playing before getting to work on this Tour Guide), you (i.e. the Player Character) start outside the entrance of a cave. The only way to go is in, and once you're in there's a rockfall that blocks the only obvious way out. To complete the game you need to fulfil two objectives: (1) locate the Golden Banana and cast it into Mount Gloom to prevent its falling into the hands of the dreaded Cabal, and (2) help the young woman you'll quickly encounter to get back out of the cave (i.e. both you and the woman must arrive back at the starting location). To fulfil the first objective you need to sail a ship round an underground lake to various destinations; to fulfil the second you need to get a TARDIS back in full working order: you'll also need the TARDIS to fulfil the first objective, traveling to locations as disparate as King Solomon's palace three thousand years in the past to an abandoned space station a thousand years in the future.