Bonus Quests and Character Class:
NOTE: The following code requires the latest version of Diablo: Hellfire. It will not work on the original version.

To access some secret Easter eggs in Hellfire, create a text file called command.txt and place it in your Hellfire directory. Next, place the following line in command.txt:

 

multitest;cowquest;theoquest;bardtest

This enables LAN and modem games, two new quests (Cow Quest and Theo Quest), and two new character classes:

The Bard reuses the Rogue's art, but can wield two weapons at once and has the Identify spell as her natural ability.

Transfer Characters from Diablo:
To transfer your characters from Diablo to Hellfire, find your save file and change the extension to .HSV. For example, if your file is called RASSILON.SV then rename it to RASSILON.HSV.