Did you unzip the file? Some versions of Windows let you open zipped folders without unzipping them, and it messes up whatever programs you use that're zipped.

Sorry, but, as someone who's distributed zipped programs before, I know exactly how common that error is. Looking at my copy, it would seem define.dat belongs in a subfolder called Script. You said yours is in the same folder. This is likely a problem.

Most unzip programs have an option that keeps the directory structure. You might want to check if that's set in your unzipper and try extracting again...

Check your directory structure anyhow, just in case... In your top level Ivan directory you should have these files: AUTHORS ChangeLog IVAN.exe LICENSING README msvcrt.dll COPYING IvanWin050.zip NEWS SDL.dll msvcp50.dll You should also have the following directories: Graphics Script you need these files in the "Graphics" directory: Char.pcx FOW.pcx Humanoid.PCX Menu.pcx WTerra.pcx Cursor.pcx Font.pcx Icon.bmp OLTerra.pcx Effect.pcx GLTerra.pcx Item.PCX Symbol.pcx and these files in the "Script" directory: char.dat dungeon.dat item.dat olterra.dat define.dat glterra.dat material.dat On the whole, I think that should work for any version of Windows, unless you've done something really strange to your default environment variables. If it doesn't work, check your current environment variables (right click on My Computer, go to one of the tabs in "properties" - I can't recall which one right now), check the "path" values, and post them here. Maybe someone more knowledgeable than me will be able to help you after that. If it turns out that I'm leading you on a wild goose chase with the environment variables thing, don't blame me, blame the beers I drank tonight before posting anything - "beer is the mind killer, beer is the little-death that brings total obliteration".