What Could Have Been: Mid Boss was originally going to be a hulking monster who easily cried and Laharl originally had a sister. The designs of proto-Mid Boss and Laharl's little sister would make it's way into the anime as two monster guarding the dump Flonne finds Laharl in and Maharl, a demon trying to pose as Laharl's sister, respectively.
Originally, the series was supposed to be a space-set rail shooter series, similar to Star Fox. Several elements from the original idea can be seen in-game, such as the gun turrets from Chapter 13 and the Scout's Geo Cannon ability.