Diablo Hints & Cheats

There are three different difficulties in Diablo: Normal, Nightmare and Hell. Upon completing Normal, the player then has the option to play on Nightmare, and once Nightmare is finished, Hell opens up.

In a two player game, toss any item from your inventory to the other person. Have them pick it up, and save. Go and sell the item for gold, and save your character. Start a new game, get the item back, and you have money for nothing
OR
Take an elixer and toss it to the other player. Have them save their game. Get the elixer back, and drink it. Save.
Start a new game, and reverse the process if you want. More effective with multiple elixers.