Source files of the game, you cant extract extra files using ffdec in the .exe version of the game.
Barbarian Onslaught: The Secret of Steel is now open source! You can modify the game if you want, just be aware of the attached license!
The "Barbarian Onslaught: The Secret of Steel is © MythoLogic Interactive"
Check MythoLogic Interactive forums for more info and to talk about the game.