Indiana Jones is determined to find the lost Ark of the Covenant, and has travelled to Egypt to look for it. Somewhere in the marketplace are clues and tools that will help Indy on his adventure, but first Indy must figure out how to use those tools and interpret those clues. As he learns, with your help, what each item can do, he will discover new areas to explore, new items to acquire, and new hints to decipher.
There are two important things to remember in this quest. One, Indy can only carry six items at a time, and cannot use more than one item at a time. Two, any item Indy drops or uses up can be found again where it was originally picked up... though getting back to that area may be easier said than done!
If you're stuck (or impatient), there are plenty of guides on the Internet that will walk you through the different areas of the game. Remember, though, this is a puzzle and adventure game. Figuring out the rules is in fact one of the rules of the game!